diff --git a/Neos.Flow.Log/Classes/Backend/AbstractBackend.php b/Neos.Flow.Log/Classes/Backend/AbstractBackend.php
index 6279d6cd85..1e879d90db 100644
--- a/Neos.Flow.Log/Classes/Backend/AbstractBackend.php
+++ b/Neos.Flow.Log/Classes/Backend/AbstractBackend.php
@@ -42,7 +42,7 @@ abstract class AbstractBackend implements BackendInterface
      */
     public function __construct($options = [])
     {
-        if (is_array($options) || $options instanceof \ArrayAccess) {
+        if (is_iterable($options)) {
             foreach ($options as $optionKey => $optionValue) {
                 $methodName = 'set' . ucfirst($optionKey);
                 if (method_exists($this, $methodName)) {
diff --git a/Neos.Flow.Log/Classes/Backend/AnsiConsoleBackend.php b/Neos.Flow.Log/Classes/Backend/AnsiConsoleBackend.php
index 5749b5df81..30784f9aef 100644
--- a/Neos.Flow.Log/Classes/Backend/AnsiConsoleBackend.php
+++ b/Neos.Flow.Log/Classes/Backend/AnsiConsoleBackend.php
@@ -40,7 +40,7 @@ class AnsiConsoleBackend extends ConsoleBackend
     const END = "\033[0m";
 
     /**
-     * @var array
+     * @var array<string,string>
      */
     protected $tagFormats = [];
 
@@ -75,12 +75,7 @@ public function open(): void
     /**
      * Appends the given message along with the additional information into the log.
      *
-     * @param string $message
-     * @param int $severity
-     * @param array $additionalData
-     * @param string $packageKey
-     * @param string $className
-     * @param string $methodName
+     * @param array<mixed>|null $additionalData
      * @return void
      */
     public function append(string $message, int $severity = LOG_INFO, $additionalData = null, ?string $packageKey = null, ?string $className = null, ?string $methodName = null): void
@@ -118,7 +113,7 @@ protected function formatOutput($output)
                 } else {
                     return str_replace('|', $matches[3], $format);
                 }
-            }, $output);
+            }, $output) ?: '';
         } while ($lastOutput !== $output);
         return $output;
     }
@@ -126,7 +121,7 @@ protected function formatOutput($output)
     /**
      * @param boolean $disableAnsi
      */
-    public function setDisableAnsi($disableAnsi)
+    public function setDisableAnsi($disableAnsi): void
     {
         $this->disableAnsi = $disableAnsi;
     }
diff --git a/Neos.Flow.Log/Classes/Backend/ConsoleBackend.php b/Neos.Flow.Log/Classes/Backend/ConsoleBackend.php
index def5dd734e..1398b288c9 100644
--- a/Neos.Flow.Log/Classes/Backend/ConsoleBackend.php
+++ b/Neos.Flow.Log/Classes/Backend/ConsoleBackend.php
@@ -25,7 +25,7 @@ class ConsoleBackend extends AbstractBackend
 {
     /**
      * An array of severity labels, indexed by their integer constant
-     * @var array
+     * @var array<int,string>
      */
     protected $severityLabels;
 
@@ -61,10 +61,11 @@ public function open(): void
             LOG_DEBUG => 'DEBUG    ',
         ];
 
-        $this->streamHandle = fopen('php://' . $this->streamName, 'w');
-        if (!is_resource($this->streamHandle)) {
+        $streamHandle = fopen('php://' . $this->streamName, 'w');
+        if (!is_resource($streamHandle)) {
             throw new CouldNotOpenResourceException('Could not open stream "' . $this->streamName . '" for write access.', 1310986609);
         }
+        $this->streamHandle = $streamHandle;
     }
 
     /**
diff --git a/Neos.Flow.Log/Classes/Backend/FileBackend.php b/Neos.Flow.Log/Classes/Backend/FileBackend.php
index affc67f73e..fecc2a7978 100644
--- a/Neos.Flow.Log/Classes/Backend/FileBackend.php
+++ b/Neos.Flow.Log/Classes/Backend/FileBackend.php
@@ -27,7 +27,7 @@ class FileBackend extends AbstractBackend
 {
     /**
      * An array of severity labels, indexed by their integer constant
-     * @var array
+     * @var array<int,string>
      */
     protected $severityLabels;
 
@@ -192,6 +192,9 @@ public function open(): void
     protected function rotateLogFile(): void
     {
         $lockResource = fopen($this->logFileUrl . '.lock', 'w+');
+        if ($lockResource === false) {
+            throw new \RuntimeException(sprintf('Fatal: cannot open/create file "%s".', $this->logFileUrl . '.lock'), 1765550110);
+        }
 
         $exclusiveNonBlockingLockResult = flock($lockResource, LOCK_EX | LOCK_NB);
         if ($exclusiveNonBlockingLockResult === false) {
diff --git a/Neos.Flow.Log/Classes/PlainTextFormatter.php b/Neos.Flow.Log/Classes/PlainTextFormatter.php
index 0a15efb126..4e00147030 100644
--- a/Neos.Flow.Log/Classes/PlainTextFormatter.php
+++ b/Neos.Flow.Log/Classes/PlainTextFormatter.php
@@ -22,8 +22,8 @@ public function __construct($variable)
     }
 
     /**
-     * @param $spaces
-     * @return string
+     * @param int $spaces
+     * @return ?string
      */
     public function format($spaces = 4)
     {
diff --git a/Neos.Flow.Log/Classes/Psr/Logger.php b/Neos.Flow.Log/Classes/Psr/Logger.php
index 6ebad73f56..c1a18be6f8 100644
--- a/Neos.Flow.Log/Classes/Psr/Logger.php
+++ b/Neos.Flow.Log/Classes/Psr/Logger.php
@@ -45,7 +45,7 @@ class Logger implements LoggerInterface
     /**
      * Constructs the PSR-3 Logger.
      *
-     * @param iterable $backends
+     * @param iterable<mixed> $backends
      */
     public function __construct(iterable $backends)
     {
@@ -61,7 +61,7 @@ public function __construct(iterable $backends)
     /**
      * @param mixed $level
      * @param string|\Stringable $message
-     * @param array $context
+     * @param array<string,mixed> $context
      * @api
      */
     public function log($level, string|\Stringable $message, array $context = []): void
@@ -80,8 +80,8 @@ public function log($level, string|\Stringable $message, array $context = []): v
     }
 
     /**
-     * @param array $context
-     * @return array list of packageKey, className and methodName either string or null
+     * @param array<string,mixed> $context
+     * @return array<int,string|null> list of packageKey, className and methodName either string or null
      */
     protected function extractLegacyDataFromContext(array $context): array
     {
@@ -93,8 +93,8 @@ protected function extractLegacyDataFromContext(array $context): array
     }
 
     /**
-     * @param array $context
-     * @return array
+     * @param array<string,mixed> $context
+     * @return array<string,mixed>
      */
     protected function removeLegacyDataFromContext(array $context): array
     {
diff --git a/Neos.Flow/Classes/Reflection/ReflectionService.php b/Neos.Flow/Classes/Reflection/ReflectionService.php
index 36f7b8b76a..e7f786c605 100644
--- a/Neos.Flow/Classes/Reflection/ReflectionService.php
+++ b/Neos.Flow/Classes/Reflection/ReflectionService.php
@@ -325,8 +325,9 @@ public function getAllImplementationClassNamesForInterface(string $interfaceName
      * Searches for and returns all names of classes inheriting the specified class.
      * If no class inheriting the given class was found, an empty array is returned.
      *
-     * @param class-string $className
-     * @return array<class-string>
+     * @template T of object
+     * @param class-string<T> $className
+     * @return list<class-string<T>>
      * @throws ClassLoadingForReflectionFailedException
      * @throws InvalidClassException
      * @throws \ReflectionException
diff --git a/Neos.FluidAdaptor/Classes/Core/Cache/CacheAdaptor.php b/Neos.FluidAdaptor/Classes/Core/Cache/CacheAdaptor.php
index 43bb16e5a4..305c09501e 100644
--- a/Neos.FluidAdaptor/Classes/Core/Cache/CacheAdaptor.php
+++ b/Neos.FluidAdaptor/Classes/Core/Cache/CacheAdaptor.php
@@ -49,6 +49,7 @@ public function get($name)
      *
      * @param string $name
      * @param string $value
+     * @return void
      */
     public function set($name, $value)
     {
diff --git a/Neos.FluidAdaptor/Classes/Core/Parser/Interceptor/ResourceInterceptor.php b/Neos.FluidAdaptor/Classes/Core/Parser/Interceptor/ResourceInterceptor.php
index 286870a6ac..9334df24ad 100644
--- a/Neos.FluidAdaptor/Classes/Core/Parser/Interceptor/ResourceInterceptor.php
+++ b/Neos.FluidAdaptor/Classes/Core/Parser/Interceptor/ResourceInterceptor.php
@@ -97,7 +97,7 @@ public function process(NodeInterface $node, $interceptorPosition, ParsingState
         if (strpos($node->getText(), 'Public/') === false) {
             return $node;
         }
-        $textParts = preg_split(self::PATTERN_SPLIT_AT_RESOURCE_URIS, $node->getText(), -1, PREG_SPLIT_NO_EMPTY | PREG_SPLIT_DELIM_CAPTURE);
+        $textParts = preg_split(self::PATTERN_SPLIT_AT_RESOURCE_URIS, $node->getText(), -1, PREG_SPLIT_NO_EMPTY | PREG_SPLIT_DELIM_CAPTURE) ?: [];
         $node = new RootNode();
         foreach ($textParts as $part) {
             $matches = [];
@@ -109,7 +109,7 @@ public function process(NodeInterface $node, $interceptorPosition, ParsingState
                 if ($this->defaultPackageKey !== null) {
                     $arguments['package'] = new TextNode($this->defaultPackageKey);
                 }
-                if (isset($matches['Package']) && FlowPackageKey::isPackageKeyValid($matches['Package'])) {
+                if (FlowPackageKey::isPackageKeyValid($matches['Package'])) {
                     $arguments['package'] = new TextNode($matches['Package']);
                 }
 
@@ -127,7 +127,7 @@ public function process(NodeInterface $node, $interceptorPosition, ParsingState
     /**
      * This interceptor wants to hook into text nodes.
      *
-     * @return array Array of INTERCEPT_* constants
+     * @return array<int,int> Array of INTERCEPT_* constants
      */
     public function getInterceptionPoints()
     {
diff --git a/Neos.FluidAdaptor/Classes/Core/Parser/SyntaxTree/Expression/LegacyNamespaceExpressionNode.php b/Neos.FluidAdaptor/Classes/Core/Parser/SyntaxTree/Expression/LegacyNamespaceExpressionNode.php
index 1af2886355..cd63f4f625 100644
--- a/Neos.FluidAdaptor/Classes/Core/Parser/SyntaxTree/Expression/LegacyNamespaceExpressionNode.php
+++ b/Neos.FluidAdaptor/Classes/Core/Parser/SyntaxTree/Expression/LegacyNamespaceExpressionNode.php
@@ -24,14 +24,14 @@ class LegacyNamespaceExpressionNode extends AbstractExpressionNode implements Ex
      * Pattern which detects namespace declarations made inline.
      * syntax, e.g. {namespace neos=TYPO3\Neos\ViewHelpers}.
      */
-    public static $detectionExpression = '/{namespace\\s*([a-z0-9]+)\\s*=\\s*([a-z0-9_\\\\]+)\\s*}/i';
+    public static string $detectionExpression = '/{namespace\\s*([a-z0-9]+)\\s*=\\s*([a-z0-9_\\\\]+)\\s*}/i';
 
     /**
      * Evaluates the expression stored in this node, in the context of $renderingcontext.
      *
      * @param RenderingContextInterface $renderingContext
      * @param string $expression
-     * @param array $matches
+     * @param array<int,mixed> $matches
      * @return mixed
      */
     public static function evaluateExpression(RenderingContextInterface $renderingContext, $expression, array $matches)
diff --git a/Neos.FluidAdaptor/Classes/Core/Parser/SyntaxTree/ResourceUriNode.php b/Neos.FluidAdaptor/Classes/Core/Parser/SyntaxTree/ResourceUriNode.php
index db44103330..df88c3dfdc 100644
--- a/Neos.FluidAdaptor/Classes/Core/Parser/SyntaxTree/ResourceUriNode.php
+++ b/Neos.FluidAdaptor/Classes/Core/Parser/SyntaxTree/ResourceUriNode.php
@@ -35,18 +35,18 @@ class ResourceUriNode extends ViewHelperNode
     protected $viewHelperResolver;
 
     /**
-     * @var string
+     * @var class-string<ResourceViewHelper>
      */
     protected $viewHelperClassName = ResourceViewHelper::class;
 
     /**
      * @param ViewHelperResolver $viewHelperResolver
+     * @return void
      */
     public function injectViewHelperResolver(ViewHelperResolver $viewHelperResolver)
     {
         $this->viewHelperResolver = $viewHelperResolver;
         $this->uninitializedViewHelper = $this->viewHelperResolver->createViewHelperInstanceFromClassName($this->viewHelperClassName);
-        /** @phpstan-ignore-next-line we use internal api */
         $this->uninitializedViewHelper->setViewHelperNode($this);
         $this->argumentDefinitions = $this->viewHelperResolver->getArgumentDefinitionsForViewHelper($this->uninitializedViewHelper);
     }
diff --git a/Neos.FluidAdaptor/Classes/Core/Parser/TemplateParser.php b/Neos.FluidAdaptor/Classes/Core/Parser/TemplateParser.php
index 1ad1054885..a75e2989bd 100644
--- a/Neos.FluidAdaptor/Classes/Core/Parser/TemplateParser.php
+++ b/Neos.FluidAdaptor/Classes/Core/Parser/TemplateParser.php
@@ -16,6 +16,7 @@ public function isEscapingEnabled()
 
     /**
      * @param boolean $escapingEnabled
+     * @return void
      */
     public function setEscapingEnabled($escapingEnabled)
     {
diff --git a/Neos.FluidAdaptor/Classes/Core/Parser/TemplateProcessor/EscapingFlagProcessor.php b/Neos.FluidAdaptor/Classes/Core/Parser/TemplateProcessor/EscapingFlagProcessor.php
index fbdc9a72a1..d53ad3264d 100644
--- a/Neos.FluidAdaptor/Classes/Core/Parser/TemplateProcessor/EscapingFlagProcessor.php
+++ b/Neos.FluidAdaptor/Classes/Core/Parser/TemplateProcessor/EscapingFlagProcessor.php
@@ -25,10 +25,11 @@ class EscapingFlagProcessor implements TemplateProcessorInterface
      */
     protected $renderingContext;
 
-    public static $SCAN_PATTERN_ESCAPINGMODIFIER = '/{escapingEnabled\s*=\s*(?P<enabled>true|false)\s*}/i';
+    public static string $SCAN_PATTERN_ESCAPINGMODIFIER = '/{escapingEnabled\s*=\s*(?P<enabled>true|false)\s*}/i';
 
     /**
      * @param RenderingContextInterface $renderingContext
+     * @return void
      */
     public function setRenderingContext(RenderingContextInterface $renderingContext)
     {
@@ -56,7 +57,7 @@ public function preProcessSource($templateSource)
         if (strtolower($matches[0]['enabled']) === 'false') {
             $this->renderingContext->getTemplateParser()->setEscapingEnabled(false);
         }
-        $templateSource = preg_replace(self::$SCAN_PATTERN_ESCAPINGMODIFIER, '', $templateSource);
+        $templateSource = preg_replace(self::$SCAN_PATTERN_ESCAPINGMODIFIER, '', $templateSource) ?: '';
 
         return $templateSource;
     }
diff --git a/Neos.FluidAdaptor/Classes/Core/Parser/TemplateProcessor/NamespaceDetectionTemplateProcessor.php b/Neos.FluidAdaptor/Classes/Core/Parser/TemplateProcessor/NamespaceDetectionTemplateProcessor.php
index b6c18f2664..3c813c0c01 100644
--- a/Neos.FluidAdaptor/Classes/Core/Parser/TemplateProcessor/NamespaceDetectionTemplateProcessor.php
+++ b/Neos.FluidAdaptor/Classes/Core/Parser/TemplateProcessor/NamespaceDetectionTemplateProcessor.php
@@ -29,7 +29,7 @@ class NamespaceDetectionTemplateProcessor extends FluidNamespaceDetectionTemplat
     /**
      * Extension of the default pattern for dynamic tags including namespaces with uppercase letters.
      */
-    public static $EXTENDED_SPLIT_PATTERN_TEMPLATE_DYNAMICTAGS = '/
+    public static string $EXTENDED_SPLIT_PATTERN_TEMPLATE_DYNAMICTAGS = '/
 		(
 			(?: <\/?                                      # Start dynamic tags
 					(?:(?:[a-zA-Z0-9\\.]*):[a-zA-Z0-9\\.]+)  # A tag consists of the namespace prefix and word characters
@@ -75,7 +75,7 @@ public function preProcessSource($templateSource)
      */
     public function protectCDataSectionsFromParser(string $templateSource)
     {
-        $parts = preg_split('/(\<\!\[CDATA\[|\]\]\>)/', $templateSource, -1, PREG_SPLIT_DELIM_CAPTURE);
+        $parts = preg_split('/(\<\!\[CDATA\[|\]\]\>)/', $templateSource, -1, PREG_SPLIT_DELIM_CAPTURE) ?: [];
         $balance = 0;
         $content = '';
         $resultingParts = [];
@@ -127,7 +127,7 @@ public function protectCDataSectionsFromParser(string $templateSource)
     public function throwExceptionsForUnhandledNamespaces(string $templateSource): void
     {
         $viewHelperResolver = $this->renderingContext->getViewHelperResolver();
-        $splitTemplate = preg_split(static::$EXTENDED_SPLIT_PATTERN_TEMPLATE_DYNAMICTAGS, $templateSource, -1, PREG_SPLIT_DELIM_CAPTURE | PREG_SPLIT_NO_EMPTY);
+        $splitTemplate = preg_split(static::$EXTENDED_SPLIT_PATTERN_TEMPLATE_DYNAMICTAGS, $templateSource, -1, PREG_SPLIT_DELIM_CAPTURE | PREG_SPLIT_NO_EMPTY) ?: [];
         foreach ($splitTemplate as $templateElement) {
             if (preg_match(Patterns::$SCAN_PATTERN_TEMPLATE_VIEWHELPERTAG, $templateElement, $matchedVariables) > 0) {
                 if (!$viewHelperResolver->isNamespaceValidOrIgnored($matchedVariables['NamespaceIdentifier'])) {
@@ -148,11 +148,9 @@ public function throwExceptionsForUnhandledNamespaces(string $templateSource): v
             foreach ($sections as $section) {
                 if (preg_match(Patterns::$SCAN_PATTERN_SHORTHANDSYNTAX_OBJECTACCESSORS, $section, $matchedVariables) > 0) {
                     preg_match_all(Patterns::$SPLIT_PATTERN_SHORTHANDSYNTAX_VIEWHELPER, $section, $shorthandViewHelpers, PREG_SET_ORDER);
-                    if (is_array($shorthandViewHelpers) === true) {
-                        foreach ($shorthandViewHelpers as $shorthandViewHelper) {
-                            if (!$viewHelperResolver->isNamespaceValidOrIgnored($shorthandViewHelper['NamespaceIdentifier'])) {
-                                throw new UnknownNamespaceException('Unknown Namespace: ' . $shorthandViewHelper['NamespaceIdentifier']);
-                            }
+                    foreach ($shorthandViewHelpers as $shorthandViewHelper) {
+                        if (!$viewHelperResolver->isNamespaceValidOrIgnored($shorthandViewHelper['NamespaceIdentifier'])) {
+                            throw new UnknownNamespaceException('Unknown Namespace: ' . $shorthandViewHelper['NamespaceIdentifier']);
                         }
                     }
                 }
diff --git a/Neos.FluidAdaptor/Classes/Core/Rendering/RenderingContext.php b/Neos.FluidAdaptor/Classes/Core/Rendering/RenderingContext.php
index 3c68fb552b..2df3c433fc 100644
--- a/Neos.FluidAdaptor/Classes/Core/Rendering/RenderingContext.php
+++ b/Neos.FluidAdaptor/Classes/Core/Rendering/RenderingContext.php
@@ -25,6 +25,7 @@
 use Neos\FluidAdaptor\Core\ViewHelper\ViewHelperResolver;
 use Neos\FluidAdaptor\View\TemplatePaths;
 use TYPO3Fluid\Fluid\Core\Parser\Configuration;
+use TYPO3Fluid\Fluid\Core\Parser\SyntaxTree\Expression\AbstractExpressionNode;
 use TYPO3Fluid\Fluid\Core\Parser\SyntaxTree\Expression\CastingExpressionNode;
 use TYPO3Fluid\Fluid\Core\Parser\SyntaxTree\Expression\MathExpressionNode;
 use TYPO3Fluid\Fluid\Core\Parser\SyntaxTree\Expression\TernaryExpressionNode;
@@ -42,7 +43,7 @@ class RenderingContext extends FluidRenderingContext implements FlowAwareRenderi
      * which will be consulted when an expression does not match
      * any built-in parser expression types.
      *
-     * @var array
+     * @var array<class-string<AbstractExpressionNode>>
      */
     protected $expressionNodeTypes = [
         LegacyNamespaceExpressionNode::class,
@@ -81,7 +82,7 @@ class RenderingContext extends FluidRenderingContext implements FlowAwareRenderi
     /**
      * RenderingContext constructor.
      *
-     * @param array $options
+     * @param array<string,mixed> $options
      */
     public function __construct(array $options = [])
     {
@@ -99,6 +100,7 @@ public function __construct(array $options = [])
 
     /**
      * @param ObjectManagerInterface $objectManager
+     * @return void
      */
     public function injectObjectManager(ObjectManagerInterface $objectManager)
     {
@@ -116,7 +118,7 @@ public function getControllerContext()
     /**
      * @param ControllerContext $controllerContext
      */
-    public function setControllerContext($controllerContext)
+    public function setControllerContext($controllerContext): void
     {
         $this->controllerContext = $controllerContext;
         $request = $controllerContext->getRequest();
diff --git a/Neos.FluidAdaptor/Classes/Core/ViewHelper/AbstractConditionViewHelper.php b/Neos.FluidAdaptor/Classes/Core/ViewHelper/AbstractConditionViewHelper.php
index 052ef09e98..95010126c0 100644
--- a/Neos.FluidAdaptor/Classes/Core/ViewHelper/AbstractConditionViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/Core/ViewHelper/AbstractConditionViewHelper.php
@@ -45,6 +45,7 @@ abstract class AbstractConditionViewHelper extends AbstractViewHelper
 
     /**
      * Initializes the "then" and "else" arguments
+     * @return void
      */
     public function initializeArguments()
     {
@@ -66,18 +67,19 @@ public function initializeArguments()
      * subclasses that will be using this base class in the future. Let this
      * be a warning if someone considers changing this method signature!
      *
-     * @param array|NULL $arguments
+     * @param array<mixed>|NULL $arguments
      * @param RenderingContextInterface $renderingContext
      * @return boolean
      * @api
      */
     protected static function evaluateCondition($arguments, RenderingContextInterface $renderingContext)
     {
-        return (boolean)$arguments['condition'];
+        // fallback value derived from registerArgument default value
+        return (boolean)($arguments['condition'] ?? false);
     }
 
     /**
-     * @param array $arguments
+     * @param array<string,mixed> $arguments
      * @param \Closure $renderChildrenClosure
      * @param RenderingContextInterface $renderingContext
      * @return mixed
@@ -103,8 +105,8 @@ public static function renderStatic(array $arguments, \Closure $renderChildrenCl
     }
 
     /**
-     * @param array $closures
-     * @param array $conditionClosures
+     * @param array<mixed> $closures
+     * @param array<mixed> $conditionClosures
      * @param RenderingContextInterface $renderingContext
      * @return string
      */
@@ -236,7 +238,7 @@ public function compile($argumentsName, $closureName, &$initializationPhpCode, V
 
     /**
      * @param boolean $isConditionFullfilled
-     * @param array $arguments
+     * @param array<string,mixed> $arguments
      * @param RenderingContextInterface $renderingContext
      * @return mixed
      */
diff --git a/Neos.FluidAdaptor/Classes/Core/ViewHelper/AbstractLocaleAwareViewHelper.php b/Neos.FluidAdaptor/Classes/Core/ViewHelper/AbstractLocaleAwareViewHelper.php
index 5f33d1e651..db22b521e4 100644
--- a/Neos.FluidAdaptor/Classes/Core/ViewHelper/AbstractLocaleAwareViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/Core/ViewHelper/AbstractLocaleAwareViewHelper.php
@@ -38,6 +38,7 @@ public function __construct()
 
     /**
      * @param I18n\Service $localizationService
+     * @return void
      */
     public function injectLocalizationService(I18n\Service $localizationService)
     {
diff --git a/Neos.FluidAdaptor/Classes/Core/ViewHelper/AbstractTagBasedViewHelper.php b/Neos.FluidAdaptor/Classes/Core/ViewHelper/AbstractTagBasedViewHelper.php
index d4743808a6..2ce96b048d 100644
--- a/Neos.FluidAdaptor/Classes/Core/ViewHelper/AbstractTagBasedViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/Core/ViewHelper/AbstractTagBasedViewHelper.php
@@ -32,7 +32,7 @@ abstract class AbstractTagBasedViewHelper extends AbstractViewHelper
     /**
      * Names of all registered tag attributes
      *
-     * @var array
+     * @var array<mixed>
      */
     private static $tagAttributes = [];
 
@@ -156,7 +156,7 @@ protected function registerUniversalTagAttributes()
      * which in the default implementation will throw an error
      * about "undeclared argument used".
      *
-     * @param array $arguments
+     * @param array<string,string|\Traversable<mixed>|array<mixed>|null> $arguments
      * @return void
      */
     public function handleAdditionalArguments(array $arguments)
diff --git a/Neos.FluidAdaptor/Classes/Core/ViewHelper/ViewHelperResolver.php b/Neos.FluidAdaptor/Classes/Core/ViewHelper/ViewHelperResolver.php
index 8351bfa4f1..3ec15a4742 100644
--- a/Neos.FluidAdaptor/Classes/Core/ViewHelper/ViewHelperResolver.php
+++ b/Neos.FluidAdaptor/Classes/Core/ViewHelper/ViewHelperResolver.php
@@ -15,6 +15,7 @@
 use Neos\Flow\ObjectManagement\ObjectManagerInterface;
 use Neos\Flow\Package\Package;
 use Neos\Flow\Package\PackageManager;
+use TYPO3Fluid\Fluid\Core\ViewHelper\ViewHelperInterface;
 
 /**
  * Class ViewHelperResolver
@@ -49,16 +50,20 @@ class ViewHelperResolver extends \TYPO3Fluid\Fluid\Core\ViewHelper\ViewHelperRes
      * will look for classes in both namespaces starting
      * from the bottom.
      *
-     * @var array
+     * @var array<mixed>
      */
     protected $namespaces = [];
 
     /**
      * @Flow\InjectConfiguration(path="namespaces")
-     * @var array
+     * @var array<mixed>
      */
     protected $namespacesFromConfiguration;
 
+    /**
+     * @param int $reason
+     * @return void
+     */
     public function initializeObject($reason)
     {
         if ($reason === ObjectManagerInterface::INITIALIZATIONCAUSE_RECREATED) {
@@ -83,8 +88,9 @@ public function initializeObject($reason)
     }
 
     /**
-     * @param string $viewHelperClassName
-     * @return \TYPO3Fluid\Fluid\Core\ViewHelper\ViewHelperInterface
+     * @template T of ViewHelperInterface
+     * @param class-string<T> $viewHelperClassName
+     * @return T
      */
     public function createViewHelperInstanceFromClassName($viewHelperClassName)
     {
@@ -125,7 +131,7 @@ public function createViewHelperInstanceFromClassName($viewHelperClassName)
      * when you use this method you should always include the "f" namespace.
      *
      * @param string $identifier
-     * @param string|array $phpNamespace
+     * @param string|array<string>|null $phpNamespace
      * @return void
      */
     public function addNamespace($identifier, $phpNamespace)
@@ -148,6 +154,7 @@ public function addNamespace($identifier, $phpNamespace)
     /**
      * @param string $identifier
      * @param string $phpNamespace
+     * @return void
      */
     protected function addNamespaceInternal($identifier, $phpNamespace)
     {
diff --git a/Neos.FluidAdaptor/Classes/Core/Widget/AbstractWidgetController.php b/Neos.FluidAdaptor/Classes/Core/Widget/AbstractWidgetController.php
index c7b38b4a80..4c07eab1e2 100644
--- a/Neos.FluidAdaptor/Classes/Core/Widget/AbstractWidgetController.php
+++ b/Neos.FluidAdaptor/Classes/Core/Widget/AbstractWidgetController.php
@@ -36,7 +36,7 @@ abstract class AbstractWidgetController extends ActionController
     /**
      * Configuration for this widget.
      *
-     * @var array
+     * @var array<mixed>
      * @api
      */
     protected $widgetConfiguration;
@@ -60,7 +60,6 @@ abstract class AbstractWidgetController extends ActionController
      */
     public function processRequest(ActionRequest $request): ResponseInterface
     {
-        /** @var WidgetContext $widgetContext */
         $widgetContext = $request->getInternalArgument('__widgetContext');
         if (!$widgetContext instanceof WidgetContext) {
             throw new WidgetContextNotFoundException('The widget context could not be found in the request.', 1307450180);
diff --git a/Neos.FluidAdaptor/Classes/Core/Widget/AbstractWidgetViewHelper.php b/Neos.FluidAdaptor/Classes/Core/Widget/AbstractWidgetViewHelper.php
index e390a32db6..6a98bf293f 100644
--- a/Neos.FluidAdaptor/Classes/Core/Widget/AbstractWidgetViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/Core/Widget/AbstractWidgetViewHelper.php
@@ -20,6 +20,7 @@
 use Neos\FluidAdaptor\Core\ViewHelper\AbstractViewHelper;
 use Neos\FluidAdaptor\Core\ViewHelper\Facets\ChildNodeAccessInterface;
 use TYPO3Fluid\Fluid\Core\Compiler\TemplateCompiler;
+use TYPO3Fluid\Fluid\Core\Parser\SyntaxTree\NodeInterface;
 use TYPO3Fluid\Fluid\Core\Parser\SyntaxTree\RootNode;
 use TYPO3Fluid\Fluid\Core\Parser\SyntaxTree\ViewHelperNode;
 
@@ -142,7 +143,12 @@ private function initializeWidgetContext()
         $this->widgetContext->setNonAjaxWidgetConfiguration($this->getNonAjaxWidgetConfiguration());
         $this->initializeWidgetIdentifier();
 
-        $controllerObjectName = ($this->controller instanceof DependencyProxy) ? $this->controller->_getClassName() : get_class($this->controller);
+        /** @phpstan-ignore-next-line the mind of the great phpstan can and will not comprehend this */
+        if ($this->controller instanceof \Neos\Flow\ObjectManagement\DependencyInjection\DependencyProxy) {
+            $controllerObjectName = $this->controller->_getClassName();
+        } else {
+            $controllerObjectName = get_class($this->controller);
+        }
         $this->widgetContext->setControllerObjectName($controllerObjectName);
     }
 
@@ -150,7 +156,7 @@ private function initializeWidgetContext()
      * Stores the syntax tree child nodes in the Widget Context, so they can be
      * rendered with <f:widget.renderChildren> lateron.
      *
-     * @param array $childNodes The SyntaxTree Child nodes of this ViewHelper.
+     * @param array<NodeInterface> $childNodes The SyntaxTree Child nodes of this ViewHelper.
      * @return void
      */
     public function setChildNodes(array $childNodes)
@@ -166,7 +172,7 @@ public function setChildNodes(array $childNodes)
     /**
      * Generate the configuration for this widget. Override to adjust.
      *
-     * @return array
+     * @return array<mixed>
      * @api
      */
     protected function getWidgetConfiguration()
@@ -179,7 +185,7 @@ protected function getWidgetConfiguration()
      *
      * By default, returns getWidgetConfiguration(). Should become API later.
      *
-     * @return array
+     * @return array<mixed>
      */
     protected function getAjaxWidgetConfiguration()
     {
@@ -191,7 +197,7 @@ protected function getAjaxWidgetConfiguration()
      *
      * By default, returns getWidgetConfiguration(). Should become API later.
      *
-     * @return array
+     * @return array<mixed>
      */
     protected function getNonAjaxWidgetConfiguration()
     {
@@ -210,6 +216,7 @@ protected function getNonAjaxWidgetConfiguration()
      */
     protected function initiateSubRequest()
     {
+        /** @phpstan-ignore-next-line the mind of the great phpstan can and will not comprehend this */
         if ($this->controller instanceof DependencyProxy) {
             $this->controller->_activateDependency();
         }
diff --git a/Neos.FluidAdaptor/Classes/Core/Widget/AjaxWidgetContextHolder.php b/Neos.FluidAdaptor/Classes/Core/Widget/AjaxWidgetContextHolder.php
index f78a163c2f..81a7077866 100644
--- a/Neos.FluidAdaptor/Classes/Core/Widget/AjaxWidgetContextHolder.php
+++ b/Neos.FluidAdaptor/Classes/Core/Widget/AjaxWidgetContextHolder.php
@@ -30,7 +30,7 @@ class AjaxWidgetContextHolder
      * An array $ajaxWidgetIdentifier => $widgetContext
      * which stores the widget context.
      *
-     * @var array
+     * @var array<string,WidgetContext>
      */
     protected $widgetContexts = [];
 
diff --git a/Neos.FluidAdaptor/Classes/Core/Widget/WidgetContext.php b/Neos.FluidAdaptor/Classes/Core/Widget/WidgetContext.php
index de1beed414..2952e3e7f5 100644
--- a/Neos.FluidAdaptor/Classes/Core/Widget/WidgetContext.php
+++ b/Neos.FluidAdaptor/Classes/Core/Widget/WidgetContext.php
@@ -48,7 +48,7 @@ class WidgetContext
      * controller as $this->widgetConfiguration, if being inside an AJAX
      * request
      *
-     * @var array
+     * @var array<mixed>
      */
     protected $ajaxWidgetConfiguration;
 
@@ -57,7 +57,7 @@ class WidgetContext
      * controller as $this->widgetConfiguration, if being inside a non-AJAX
      * request
      *
-     * @var array
+     * @var array<mixed>
      */
     protected $nonAjaxWidgetConfiguration;
     /**
@@ -71,7 +71,7 @@ class WidgetContext
      * The child nodes of the Widget ViewHelper.
      * Only available inside non-AJAX requests.
      *
-     * @var RootNode
+     * @var ?RootNode
      * @Flow\Transient
      */
     protected $viewHelperChildNodes;
@@ -80,7 +80,7 @@ class WidgetContext
      * The rendering context of the ViewHelperChildNodes.
      * Only available inside non-AJAX requests.
      *
-     * @var RenderingContextInterface
+     * @var ?RenderingContextInterface
      * @Flow\Transient
      */
     protected $viewHelperChildNodeRenderingContext;
@@ -120,7 +120,7 @@ public function setAjaxWidgetIdentifier($ajaxWidgetIdentifier)
     }
 
     /**
-     * @return array
+     * @return array<mixed>
      */
     public function getWidgetConfiguration()
     {
@@ -132,7 +132,7 @@ public function getWidgetConfiguration()
     }
 
     /**
-     * @param array $ajaxWidgetConfiguration
+     * @param array<mixed> $ajaxWidgetConfiguration
      * @return void
      */
     public function setAjaxWidgetConfiguration(array $ajaxWidgetConfiguration)
@@ -141,7 +141,7 @@ public function setAjaxWidgetConfiguration(array $ajaxWidgetConfiguration)
     }
 
     /**
-     * @param array $nonAjaxWidgetConfiguration
+     * @param array<mixed> $nonAjaxWidgetConfiguration
      * @return void
      */
     public function setNonAjaxWidgetConfiguration(array $nonAjaxWidgetConfiguration)
@@ -178,7 +178,7 @@ public function setViewHelperChildNodes(RootNode $viewHelperChildNodes, Renderin
     }
 
     /**
-     * @return RootNode
+     * @return ?RootNode
      */
     public function getViewHelperChildNodes()
     {
@@ -186,7 +186,7 @@ public function getViewHelperChildNodes()
     }
 
     /**
-     * @return RenderingContextInterface
+     * @return RenderingContextInterface|null
      */
     public function getViewHelperChildNodeRenderingContext()
     {
diff --git a/Neos.FluidAdaptor/Classes/Service/AbstractGenerator.php b/Neos.FluidAdaptor/Classes/Service/AbstractGenerator.php
index 0b37087aab..6001780143 100644
--- a/Neos.FluidAdaptor/Classes/Service/AbstractGenerator.php
+++ b/Neos.FluidAdaptor/Classes/Service/AbstractGenerator.php
@@ -54,7 +54,7 @@ public function __construct()
      * Get all class names inside this namespace and return them as array.
      *
      * @param string $namespace
-     * @return array Array of all class names inside a given namespace.
+     * @return array<int,class-string<AbstractViewHelper>> Array of all class names inside a given namespace.
      */
     protected function getClassNamesInNamespace($namespace)
     {
@@ -101,7 +101,7 @@ protected function getTagNameForClass($className, $namespace)
      * @param \SimpleXMLElement $parentXmlNode Parent XML Node to add the child to
      * @param string $childNodeName Name of the child node
      * @param string $childNodeValue Value of the child node. Will be placed inside CDATA.
-     * @return \SimpleXMLElement the new element
+     * @return ?\SimpleXMLElement the new element
      */
     protected function addChildWithCData(\SimpleXMLElement $parentXmlNode, $childNodeName, $childNodeValue)
     {
@@ -110,8 +110,12 @@ protected function addChildWithCData(\SimpleXMLElement $parentXmlNode, $childNod
 
         $childNode = $domDocument->appendChild($domDocument->createElement($childNodeName));
         $childNode->appendChild($domDocument->createCDATASection($childNodeValue));
-        $childNodeTarget = $parentDomNode->ownerDocument->importNode($childNode, true);
-        $parentDomNode->appendChild($childNodeTarget);
-        return simplexml_import_dom($childNodeTarget);
+        $childNodeTarget = $parentDomNode->ownerDocument?->importNode($childNode, true);
+        if ($childNodeTarget instanceof \DOMNode) {
+            $parentDomNode->appendChild($childNodeTarget);
+            return simplexml_import_dom($childNodeTarget);
+        }
+
+        return null;
     }
 }
diff --git a/Neos.FluidAdaptor/Classes/Service/XsdGenerator.php b/Neos.FluidAdaptor/Classes/Service/XsdGenerator.php
index c67220d2e9..be4fda8617 100644
--- a/Neos.FluidAdaptor/Classes/Service/XsdGenerator.php
+++ b/Neos.FluidAdaptor/Classes/Service/XsdGenerator.php
@@ -54,7 +54,11 @@ public function generateXsd($viewHelperNamespace, $xsdNamespace)
             $this->generateXmlForClassName($className, $viewHelperNamespace, $xmlRootNode);
         }
 
-        return $xmlRootNode->asXML();
+        $result = $xmlRootNode->asXML();
+
+        return is_string($result)
+            ? $result
+            : throw new \Exception('Failed to generate xsd', 1743851104);
     }
 
     /**
@@ -75,15 +79,22 @@ protected function generateXmlForClassName($className, $viewHelperNamespace, \Si
         $tagName = $this->getTagNameForClass($className, $viewHelperNamespace);
 
         $xsdElement = $xmlRootNode->addChild('xsd:element');
+        /** @phpstan-ignore argument.type (offsetSet accepts mixed) */
         $xsdElement->offsetSet('name', $tagName);
-        $this->docCommentParser->parseDocComment($reflectionClass->getDocComment());
+        $docComment = $reflectionClass->getDocComment();
+        if ($docComment !== false) {
+            $this->docCommentParser->parseDocComment($docComment);
+        }
         $this->addDocumentation($this->docCommentParser->getDescription(), $xsdElement);
 
         $xsdComplexType = $xsdElement->addChild('xsd:complexType');
+        /** @phpstan-ignore argument.type (offsetSet accepts mixed) */
         $xsdComplexType->offsetSet('mixed', 'true');
         $xsdSequence = $xsdComplexType->addChild('xsd:sequence');
         $xsdAny = $xsdSequence->addChild('xsd:any');
+        /** @phpstan-ignore argument.type (offsetSet accepts mixed) */
         $xsdAny->offsetSet('minOccurs', '0');
+        /** @phpstan-ignore argument.type (offsetSet accepts mixed) */
         $xsdAny->offsetSet('maxOccurs', 'unbounded');
 
         $this->addAttributes($className, $xsdComplexType);
@@ -106,10 +117,13 @@ protected function addAttributes($className, \SimpleXMLElement $xsdElement)
         foreach ($argumentDefinitions as $argumentDefinition) {
             /** @var \SimpleXMLElement $xsdAttribute */
             $xsdAttribute = $xsdElement->addChild('xsd:attribute');
+            /** @phpstan-ignore argument.type (offsetSet accepts mixed) */
             $xsdAttribute->offsetSet('type', 'xsd:string');
+            /** @phpstan-ignore argument.type (offsetSet accepts mixed) */
             $xsdAttribute->offsetSet('name', $argumentDefinition->getName());
             $this->addDocumentation($argumentDefinition->getDescription(), $xsdAttribute);
             if ($argumentDefinition->isRequired()) {
+                /** @phpstan-ignore argument.type (offsetSet accepts mixed) */
                 $xsdAttribute->offsetSet('use', 'required');
             }
         }
diff --git a/Neos.FluidAdaptor/Classes/View/AbstractTemplateView.php b/Neos.FluidAdaptor/Classes/View/AbstractTemplateView.php
index 37a64bfa17..bcfc4dfb8b 100644
--- a/Neos.FluidAdaptor/Classes/View/AbstractTemplateView.php
+++ b/Neos.FluidAdaptor/Classes/View/AbstractTemplateView.php
@@ -12,7 +12,6 @@
  */
 
 use Neos\FluidAdaptor\Exception;
-use Neos\Flow\Mvc\ActionRequest;
 use Neos\Flow\Mvc\Controller\ControllerContext;
 use Neos\Flow\Mvc\View\ViewInterface;
 use Neos\FluidAdaptor\Core\Rendering\RenderingContext;
@@ -36,7 +35,7 @@ abstract class AbstractTemplateView extends \TYPO3Fluid\Fluid\View\AbstractTempl
      *         ...
      *     )
      *
-     * @var array
+     * @var array<string,mixed>
      */
     protected $supportedOptions = [
         'templateRootPathPattern' => [
@@ -101,7 +100,7 @@ abstract class AbstractTemplateView extends \TYPO3Fluid\Fluid\View\AbstractTempl
      *
      * @see $supportedOptions
      *
-     * @var array
+     * @var array<string,mixed>
      */
     protected $options = [];
 
@@ -124,6 +123,9 @@ public function assign($key, $value): self
         return parent::assign($key, $value);
     }
 
+    /**
+     * @param array<string,mixed> $values
+     */
     public function assignMultiple(array $values): self
     {
         // layer to fix incompatibility error with typo3 fluid interface
@@ -133,7 +135,7 @@ public function assignMultiple(array $values): self
     /**
      * Factory method to create an instance with given options.
      *
-     * @param array $options
+     * @param array<string,mixed> $options
      * @return static
      */
     public static function createWithOptions(array $options): self
@@ -144,7 +146,7 @@ public static function createWithOptions(array $options): self
     /**
      * Set default options based on the supportedOptions provided
      *
-     * @param array $options
+     * @param array<string,mixed>|null $options
      * @throws Exception
      */
     public function __construct(?array $options = null)
@@ -184,14 +186,9 @@ public function setControllerContext(ControllerContext $controllerContext)
             $renderingContext->setControllerContext($controllerContext);
         }
 
-
         $paths = $this->getTemplatePaths();
         $request = $controllerContext->getRequest();
 
-        if (!$request instanceof ActionRequest) {
-            return;
-        }
-
         $paths->setFormat($request->getFormat());
 
         if ($paths->getTemplateRootPaths() === [] && $paths->getLayoutRootPaths() === [] && $paths->getPartialRootPaths() === []) {
@@ -205,7 +202,7 @@ public function setControllerContext(ControllerContext $controllerContext)
      * Renders a given section.
      *
      * @param string $sectionName Name of section to render
-     * @param array $variables The variables to use
+     * @param array<string,mixed> $variables The variables to use
      * @param boolean $ignoreUnknown Ignore an unknown section and just return an empty string
      * @return string rendered template for the section
      * @throws \Neos\FluidAdaptor\View\Exception\InvalidSectionException
@@ -217,13 +214,14 @@ public function renderSection($sectionName, array $variables = [], $ignoreUnknow
             $variables = $this->getRenderingContext()->getVariableProvider()->getAll();
         }
 
+        /** @phpstan-ignore argument.type (we assume Fluid actually supports \ArrayAccess here, too) */
         return parent::renderSection($sectionName, $variables, $ignoreUnknown);
     }
 
     /**
      * Validate options given to this view.
      *
-     * @param array $options
+     * @param array<string,mixed> $options
      * @return void
      * @throws Exception
      */
@@ -250,7 +248,7 @@ function ($supportedOptionData, $supportedOptionName, $options) {
      * Merges the given options with the default values
      * and sets the resulting options in this object.
      *
-     * @param array $options
+     * @param array<string,mixed> $options
      * @return void
      */
     protected function setOptions(array $options)
diff --git a/Neos.FluidAdaptor/Classes/View/StandaloneView.php b/Neos.FluidAdaptor/Classes/View/StandaloneView.php
index 6fdb79413a..bcf401ae2f 100644
--- a/Neos.FluidAdaptor/Classes/View/StandaloneView.php
+++ b/Neos.FluidAdaptor/Classes/View/StandaloneView.php
@@ -51,7 +51,7 @@ class StandaloneView extends AbstractTemplateView
     protected $environment;
 
     /**
-     * @var ActionRequest
+     * @var ?ActionRequest
      */
     protected $request;
 
@@ -64,7 +64,7 @@ class StandaloneView extends AbstractTemplateView
     /**
      * Factory method to create an instance with given options.
      *
-     * @param array $options
+     * @param array<string,mixed> $options
      * @return static
      */
     public static function createWithOptions(array $options): self
@@ -75,8 +75,8 @@ public static function createWithOptions(array $options): self
     /**
      * Constructor
      *
-     * @param ActionRequest $request The current action request. If none is specified it will be created from the environment.
-     * @param array $options
+     * @param ?ActionRequest $request The current action request. If none is specified it will be created from the environment.
+     * @param array<string,mixed> $options
      * @throws \Neos\FluidAdaptor\Exception
      */
     public function __construct(?ActionRequest $request = null, array $options = [])
@@ -115,6 +115,7 @@ public function initializeObject()
 
     /**
      * @param string $templateName
+     * @return void
      */
     public function setTemplate($templateName)
     {
@@ -130,6 +131,9 @@ public function setTemplate($templateName)
      */
     public function setFormat($format)
     {
+        if (!$this->request) {
+            throw new \Exception('Cannot set format without a request', 1743856310);
+        }
         $this->request->setFormat($format);
         $this->baseRenderingContext->getTemplatePaths()->setFormat($format);
     }
@@ -137,18 +141,18 @@ public function setFormat($format)
     /**
      * Returns the format of the current request (defaults is "html")
      *
-     * @return string $format
+     * @return ?string $format
      * @api
      */
     public function getFormat()
     {
-        return $this->request->getFormat();
+        return $this->request?->getFormat();
     }
 
     /**
      * Returns the current request object
      *
-     * @return ActionRequest
+     * @return ?ActionRequest
      */
     public function getRequest()
     {
@@ -177,12 +181,20 @@ public function setTemplatePathAndFilename($templatePathAndFilename)
     /**
      * Returns the absolute path to a Fluid template file if it was specified with setTemplatePathAndFilename() before
      *
-     * @return string Fluid template path
+     * @return ?string Fluid template path
      * @api
      */
     public function getTemplatePathAndFilename()
     {
-        return $this->baseRenderingContext->getTemplatePaths()->resolveTemplateFileForControllerAndActionAndFormat($this->request->getControllerName(), $this->request->getControllerActionName(), $this->request->getFormat());
+        return $this->request
+            ? $this->baseRenderingContext
+                ->getTemplatePaths()
+                ->resolveTemplateFileForControllerAndActionAndFormat(
+                    $this->request->getControllerName(),
+                    $this->request->getControllerActionName(),
+                    $this->request->getFormat()
+                )
+            : null;
     }
 
     /**
@@ -225,7 +237,7 @@ public function setLayoutRootPaths(array $layoutRootPaths)
     /**
      * Resolves the layout root to be used inside other paths.
      *
-     * @return array Fluid layout root paths
+     * @return array<string> Fluid layout root paths
      * @throws InvalidTemplateResourceException
      * @api
      */
@@ -262,7 +274,7 @@ public function setPartialRootPaths(array $partialRootPaths)
     /**
      * Returns the absolute path to the folder that contains Fluid partial files
      *
-     * @return array Fluid partial root paths
+     * @return array<string> Fluid partial root paths
      * @throws InvalidTemplateResourceException
      * @api
      */
diff --git a/Neos.FluidAdaptor/Classes/View/TemplatePaths.php b/Neos.FluidAdaptor/Classes/View/TemplatePaths.php
index ee45bae7eb..0fac66a3e2 100644
--- a/Neos.FluidAdaptor/Classes/View/TemplatePaths.php
+++ b/Neos.FluidAdaptor/Classes/View/TemplatePaths.php
@@ -52,7 +52,7 @@ class TemplatePaths extends \TYPO3Fluid\Fluid\View\TemplatePaths
     ];
 
     /**
-     * @var array
+     * @var array<string,mixed>
      */
     protected $options = [];
 
@@ -61,6 +61,9 @@ class TemplatePaths extends \TYPO3Fluid\Fluid\View\TemplatePaths
      */
     protected $packageManager;
 
+    /**
+     * @param array<string,mixed> $options
+     */
     public function __construct(array $options = [])
     {
         foreach ($options as $optionName => $optionValue) {
@@ -70,6 +73,7 @@ public function __construct(array $options = [])
 
     /**
      * @param PackageManager $packageManager
+     * @return void
      */
     public function injectPackageManager(PackageManager $packageManager)
     {
@@ -86,6 +90,7 @@ public function getTemplateRootPathPattern(): string
 
     /**
      * @param string $templateRootPathPattern
+     * @return void
      */
     public function setTemplateRootPathPattern(string $templateRootPathPattern)
     {
@@ -94,6 +99,7 @@ public function setTemplateRootPathPattern(string $templateRootPathPattern)
 
     /**
      * @param string $layoutRootPathPattern
+     * @return void
      */
     public function setLayoutRootPathPattern(string $layoutRootPathPattern)
     {
@@ -102,6 +108,7 @@ public function setLayoutRootPathPattern(string $layoutRootPathPattern)
 
     /**
      * @param string $partialRootPathPattern
+     * @return void
      */
     public function setPartialRootPathPattern(string $partialRootPathPattern)
     {
@@ -110,6 +117,7 @@ public function setPartialRootPathPattern(string $partialRootPathPattern)
 
     /**
      * @param string $templateRootPath
+     * @return void
      */
     public function setTemplateRootPath($templateRootPath)
     {
@@ -119,7 +127,7 @@ public function setTemplateRootPath($templateRootPath)
     /**
      * Resolves the template root to be used inside other paths.
      *
-     * @return array Path(s) to template root directory
+     * @return array<string> Path(s) to template root directory
      */
     public function getTemplateRootPaths()
     {
@@ -140,7 +148,7 @@ public function getTemplateRootPaths()
     }
 
     /**
-     * @return array
+     * @return array<string>
      */
     public function getLayoutRootPaths()
     {
@@ -160,6 +168,9 @@ public function getLayoutRootPaths()
         return [$layoutRootPath];
     }
 
+    /**
+     * @return array<string>
+     */
     public function getPartialRootPaths()
     {
         if ($this->partialRootPaths !== []) {
@@ -180,6 +191,7 @@ public function getPartialRootPaths()
 
     /**
      * @param string $layoutRootPath
+     * @return void
      */
     public function setLayoutRootPath($layoutRootPath)
     {
@@ -188,6 +200,7 @@ public function setLayoutRootPath($layoutRootPath)
 
     /**
      * @param string $partialRootPath
+     * @return void
      */
     public function setPartialRootPath($partialRootPath)
     {
@@ -204,6 +217,7 @@ public function getPatternReplacementVariables()
 
     /**
      * @param string[] $patternReplacementVariables
+     * @return void
      */
     public function setPatternReplacementVariables($patternReplacementVariables)
     {
@@ -389,10 +403,10 @@ protected function sanitizePath($path)
      * replaced by the current request format, and once with ."@format" stripped off.
      *
      * @param string $pattern Pattern to be resolved
-     * @param array $patternReplacementVariables The variables to replace in the pattern
+     * @param array<string,mixed> $patternReplacementVariables The variables to replace in the pattern
      * @param boolean $bubbleControllerAndSubpackage if true, then we successively split off parts from "@controller" and "@subpackage" until both are empty.
      * @param boolean $formatIsOptional if true, then half of the resulting strings will have ."@format" stripped off, and the other half will have it.
-     * @return array unix style paths
+     * @return array<mixed> unix style paths
      */
     protected function expandGenericPathPattern($pattern, array $patternReplacementVariables, $bubbleControllerAndSubpackage, $formatIsOptional)
     {
@@ -426,10 +440,10 @@ protected function expandGenericPathPattern($pattern, array $patternReplacementV
     }
 
     /**
-     * @param array $paths
+     * @param array<mixed> $paths
      * @param string $variableName
      * @param string $variableValue
-     * @return array
+     * @return array<mixed>
      */
     protected function replacePatternVariable($paths, $variableName, $variableValue)
     {
@@ -441,11 +455,11 @@ protected function replacePatternVariable($paths, $variableName, $variableValue)
     }
 
     /**
-     * @param array $paths
+     * @param array<string> $paths
      * @param string $controllerName
      * @param string $subPackageKey
      * @param bool $bubbleControllerAndSubpackage
-     * @return array
+     * @return array<string>
      */
     protected function expandSubPackageAndController(array $paths, string $controllerName, string $subPackageKey = '', bool $bubbleControllerAndSubpackage = false): array
     {
@@ -460,7 +474,7 @@ protected function expandSubPackageAndController(array $paths, string $controlle
         $numberOfSubpackageParts = count($subpackageKeyParts);
         $subpackageReplacements = [];
         for ($i = 0; $i <= $numberOfSubpackageParts; $i++) {
-            $subpackageReplacements[] = implode('/', ($i < 0 ? $subpackageKeyParts : array_slice($subpackageKeyParts, $i)));
+            $subpackageReplacements[] = implode('/', array_slice($subpackageKeyParts, $i));
         }
         $paths = $this->expandPatterns($paths, '@subpackage', $subpackageReplacements);
 
@@ -476,10 +490,10 @@ protected function expandSubPackageAndController(array $paths, string $controlle
      * Expands the given $patterns by adding an array element for each $replacement
      * replacing occurrences of $search.
      *
-     * @param array $patterns
+     * @param array<string> $patterns
      * @param string $search
-     * @param array $replacements
-     * @return array
+     * @param array<string> $replacements
+     * @return array<int,string>
      */
     protected function expandPatterns(array $patterns, string $search, array $replacements): array
     {
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/DebugViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/DebugViewHelper.php
index 0b189fa7b2..39d42bc727 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/DebugViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/DebugViewHelper.php
@@ -78,6 +78,6 @@ public function render()
             $expressionToExamine = (is_object($expressionToExamine) ? get_class($expressionToExamine) : gettype($expressionToExamine));
         }
 
-        return \Neos\Flow\var_dump($expressionToExamine, $this->arguments['title'], true);
+        return \Neos\Flow\var_dump($expressionToExamine, $this->arguments['title'], true) ?: '';
     }
 }
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/FlashMessagesViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/FlashMessagesViewHelper.php
index 5198e6ed28..73ccbe633e 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/FlashMessagesViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/FlashMessagesViewHelper.php
@@ -105,7 +105,7 @@ public function render()
      * Render the flash messages as unsorted list. This is triggered if no "as" argument is given
      * to the ViewHelper.
      *
-     * @param list<Message> $flashMessages
+     * @param array<Message> $flashMessages
      * @return string
      */
     protected function renderAsList(array $flashMessages)
@@ -131,7 +131,7 @@ protected function renderAsList(array $flashMessages)
      * the flash messages are stored in the template inside the variable specified
      * in "as".
      *
-     * @param array $flashMessages
+     * @param array<Message> $flashMessages
      * @param string $as
      * @return string
      */
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/Form/AbstractFormFieldViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/Form/AbstractFormFieldViewHelper.php
index 489844b745..a3da57a863 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/Form/AbstractFormFieldViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/Form/AbstractFormFieldViewHelper.php
@@ -84,7 +84,6 @@ protected function getNameWithoutPrefix(): string
             $name = $this->arguments['name'];
         }
         if ($this->hasArgument('value')) {
-            /** @var object $value */
             $value = $this->arguments['value'];
             $multiple = $this->hasArgument('multiple') && $this->arguments['multiple'] === true;
             if (!$multiple
@@ -223,7 +222,7 @@ protected function getPropertyPath(): string
 
             return $formObjectName . '.' . $this->arguments['property'];
         }
-        return rtrim(preg_replace('/(\]\[|\[|\])/', '.', $this->getNameWithoutPrefix()), '.');
+        return rtrim(preg_replace('/(\]\[|\[|\])/', '.', $this->getNameWithoutPrefix()) ?: '', '.');
     }
 
     /**
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/Form/AbstractFormViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/Form/AbstractFormViewHelper.php
index 60aa6d6da6..8b0809235c 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/Form/AbstractFormViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/Form/AbstractFormViewHelper.php
@@ -41,7 +41,7 @@ public function injectPersistenceManager(PersistenceManagerInterface $persistenc
     /**
      * Prefixes / namespaces the given name with the form field prefix
      *
-     * @param string $fieldName field name to be prefixed
+     * @param ?string $fieldName field name to be prefixed
      * @return string namespaced field name
      */
     protected function prefixFieldName($fieldName)
@@ -68,13 +68,13 @@ protected function prefixFieldName($fieldName)
      * Renders a hidden form field containing the technical identity of the given object.
      *
      * @param object $object Object to create the identity field for
-     * @param string $name Name
+     * @param ?string $name Name
      * @return string A hidden field containing the Identity (UUID in Flow) of the given object or empty string if the object is unknown to the persistence framework
      * @see \Neos\Flow\Mvc\Controller\Argument::setValue()
      */
     protected function renderHiddenIdentityField($object, $name)
     {
-        if (!is_object($object) || $this->persistenceManager->isNewObject($object)) {
+        if (!is_object($object) || $this->persistenceManager->isNewObject($object) || $name === null) {
             return '';
         }
         $identifier = $this->persistenceManager->getIdentifierByObject($object);
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/Form/CheckboxViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/Form/CheckboxViewHelper.php
index d7d4e3b574..67f85cf55b 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/Form/CheckboxViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/Form/CheckboxViewHelper.php
@@ -98,7 +98,8 @@ public function render()
             if ($checked === null) {
                 $checked = false;
                 foreach ($propertyValue as $value) {
-                    if (TypeHandling::isSimpleType(TypeHandling::getTypeForValue($value))) {
+                    $typeForValue = TypeHandling::getTypeForValue($value);
+                    if (TypeHandling::isSimpleType($typeForValue)) {
                         $checked = $valueAttribute === $value;
                     } else {
                         // assume an entity
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/Form/SelectViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/Form/SelectViewHelper.php
index a2dde44370..f9c0f08933 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/Form/SelectViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/Form/SelectViewHelper.php
@@ -200,7 +200,7 @@ public function render()
     /**
      * Render the option tags.
      *
-     * @param array $options the options for the form.
+     * @param array<mixed> $options the options for the form.
      * @return string rendered tags.
      */
     protected function renderOptionTags($options)
@@ -227,7 +227,7 @@ protected function renderOptionTags($options)
     /**
      * Render the option tags.
      *
-     * @return array an associative array of options, key will be the value of the option tag
+     * @return array<string,mixed> an associative array of options, key will be the value of the option tag
      * @throws ViewHelper\Exception
      */
     protected function getOptions()
@@ -354,6 +354,7 @@ protected function getOptionValueScalar($valueElement)
             } elseif ($this->persistenceManager->getIdentifierByObject($valueElement) !== null) {
                 return $this->persistenceManager->getIdentifierByObject($valueElement);
             } else {
+                /** @phpstan-ignore cast.string (we'll try anyway -.-) */
                 return (string)$valueElement;
             }
         } else {
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/FormViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/FormViewHelper.php
index d13b5ab8bd..16820d64f4 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/FormViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/FormViewHelper.php
@@ -299,7 +299,7 @@ protected function renderHiddenReferrerFields()
         $result = chr(10);
         $request = $this->controllerContext->getRequest();
         $argumentNamespace = null;
-        if ($request instanceof ActionRequest && $request->isMainRequest() === false) {
+        if ($request->isMainRequest() === false) {
             $argumentNamespace = $request->getArgumentNamespace();
 
             $referrer = [
@@ -316,10 +316,6 @@ protected function renderHiddenReferrerFields()
             $request = $request->getParentRequest();
         }
 
-        if ($request === null) {
-            throw new \RuntimeException('No ActionRequest could be found to evaluate form argument namespace.', 1565945918);
-        }
-
         $arguments = $request->getArguments();
         if ($argumentNamespace !== null && isset($arguments[$argumentNamespace])) {
             // A sub request was there; thus we can unset the sub requests arguments,
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/Format/BytesViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/Format/BytesViewHelper.php
index 76a4b946e1..a538a7d88d 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/Format/BytesViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/Format/BytesViewHelper.php
@@ -72,7 +72,7 @@ class BytesViewHelper extends AbstractLocaleAwareViewHelper
 
     /**
      * @param float $bytes
-     * @return array<int, float|string>
+     * @return array{0: float, 1: string}
      */
     protected static function maximizeUnit(float $bytes): array
     {
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/Format/CaseViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/Format/CaseViewHelper.php
index 9dc3ecd2c2..8eefa16a80 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/Format/CaseViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/Format/CaseViewHelper.php
@@ -123,7 +123,7 @@ public function render()
     }
 
     /**
-     * @param array $arguments
+     * @param array<string,mixed> $arguments
      * @param \Closure $renderChildrenClosure
      * @param RenderingContextInterface $renderingContext
      * @return string
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/Format/CropViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/Format/CropViewHelper.php
index 4ab2986948..e9de2cb5be 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/Format/CropViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/Format/CropViewHelper.php
@@ -78,7 +78,7 @@ public function render()
     }
 
     /**
-     * @param array $arguments
+     * @param array<string,mixed> $arguments
      * @param \Closure $renderChildrenClosure
      * @param RenderingContextInterface $renderingContext
      * @return string
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/Format/HtmlentitiesDecodeViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/Format/HtmlentitiesDecodeViewHelper.php
index 0316b42dcc..660c7f2fee 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/Format/HtmlentitiesDecodeViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/Format/HtmlentitiesDecodeViewHelper.php
@@ -79,7 +79,7 @@ public function render()
     /**
      * Applies html_entity_decode() on the specified value.
      *
-     * @param array $arguments
+     * @param array<string,mixed> $arguments
      * @param \Closure $renderChildrenClosure
      * @param RenderingContextInterface $renderingContext
      * @return string|mixed
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/Format/HtmlentitiesViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/Format/HtmlentitiesViewHelper.php
index a1d67c8532..0f0dbe84ed 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/Format/HtmlentitiesViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/Format/HtmlentitiesViewHelper.php
@@ -79,7 +79,7 @@ public function render()
     /**
      * Applies htmlentities() on the specified value.
      *
-     * @param array $arguments
+     * @param array<string,mixed> $arguments
      * @param \Closure $renderChildrenClosure
      * @param RenderingContextInterface $renderingContext
      * @return string|mixed
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/Format/JsonViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/Format/JsonViewHelper.php
index 87c216d4d5..d8c7b228e4 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/Format/JsonViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/Format/JsonViewHelper.php
@@ -86,7 +86,7 @@ public function render()
             $options = $options | JSON_FORCE_OBJECT;
         }
 
-        return json_encode($value, $options);
+        return json_encode($value, $options | JSON_THROW_ON_ERROR);
     }
 
     /**
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/Format/PaddingViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/Format/PaddingViewHelper.php
index 476db7b55e..cc37d1f089 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/Format/PaddingViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/Format/PaddingViewHelper.php
@@ -79,7 +79,7 @@ public function render()
     /**
      * Applies str_pad() on the specified value.
      *
-     * @param array $arguments
+     * @param array<string,mixed> $arguments
      * @param \Closure $renderChildrenClosure
      * @param RenderingContextInterface $renderingContext
      * @return string
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/Format/UrlencodeViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/Format/UrlencodeViewHelper.php
index f312b713b2..f0650790bb 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/Format/UrlencodeViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/Format/UrlencodeViewHelper.php
@@ -72,7 +72,7 @@ public function render()
     /**
      * Applies rawurlencode() on the specified value.
      *
-     * @param array $arguments
+     * @param array<string,mixed> $arguments
      * @param \Closure $renderChildrenClosure
      * @param RenderingContextInterface $renderingContext
      * @return string|mixed
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/RenderChildrenViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/RenderChildrenViewHelper.php
index 9d35aca2ef..1041792388 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/RenderChildrenViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/RenderChildrenViewHelper.php
@@ -74,7 +74,7 @@ public function render(): string
         $widgetChildNodes = $this->getWidgetChildNodes();
 
         $this->addArgumentsToTemplateVariableContainer($this->arguments['arguments']);
-        $output = $widgetChildNodes->evaluate($renderingContext);
+        $output = $widgetChildNodes?->evaluate($renderingContext) ?: '';
         $this->removeArgumentsFromTemplateVariableContainer($this->arguments['arguments']);
 
         return $output;
@@ -97,10 +97,10 @@ protected function getWidgetRenderingContext(): RenderingContextInterface
     }
 
     /**
-     * @return RootNode
+     * @return ?RootNode
      * @throws WidgetContextNotFoundException
      */
-    protected function getWidgetChildNodes(): RootNode
+    protected function getWidgetChildNodes(): ?RootNode
     {
         return $this->getWidgetContext()->getViewHelperChildNodes();
     }
@@ -123,7 +123,7 @@ protected function getWidgetContext(): WidgetContext
     /**
      * Add the given arguments to the TemplateVariableContainer of the widget.
      *
-     * @param array $arguments
+     * @param array<string,mixed> $arguments
      * @return void
      * @throws RenderingContextNotFoundException
      * @throws WidgetContextNotFoundException
@@ -139,7 +139,7 @@ protected function addArgumentsToTemplateVariableContainer(array $arguments): vo
     /**
      * Remove the given arguments from the TemplateVariableContainer of the widget.
      *
-     * @param array $arguments
+     * @param array<string,mixed> $arguments
      * @return void
      * @throws RenderingContextNotFoundException
      * @throws WidgetContextNotFoundException
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/Security/IfAccessViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/Security/IfAccessViewHelper.php
index 225621a2e7..5a4737fd35 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/Security/IfAccessViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/Security/IfAccessViewHelper.php
@@ -15,7 +15,6 @@
 use Neos\Flow\Security\Authorization\PrivilegeManagerInterface;
 use Neos\Flow\Security\Context;
 use Neos\FluidAdaptor\Core\Rendering\FlowAwareRenderingContextInterface;
-use Neos\FluidAdaptor\Core\Rendering\RenderingContext;
 use Neos\FluidAdaptor\Core\ViewHelper\AbstractConditionViewHelper;
 use TYPO3Fluid\Fluid\Core\Rendering\RenderingContextInterface;
 
@@ -56,6 +55,7 @@ class IfAccessViewHelper extends AbstractConditionViewHelper
 {
     /**
      * Initializes the "then" and "else" arguments
+     * @return void
      */
     public function initializeArguments()
     {
@@ -80,9 +80,9 @@ public function render()
     }
 
     /**
-     * @param array $arguments
+     * @param array<string,mixed> $arguments
      * @param \Closure $renderChildrenClosure
-     * @param RenderingContextInterface $renderingContext
+     * @param FlowAwareRenderingContextInterface&RenderingContextInterface $renderingContext
      * @return mixed
      */
     public static function renderStatic(array $arguments, \Closure $renderChildrenClosure, RenderingContextInterface $renderingContext)
@@ -91,28 +91,31 @@ public static function renderStatic(array $arguments, \Closure $renderChildrenCl
     }
 
     /**
-     * @param array|null $arguments
+     * @param array<string,mixed>|null $arguments
      * @param FlowAwareRenderingContextInterface&RenderingContextInterface $renderingContext
      * @return boolean
      */
     protected static function evaluateCondition($arguments, RenderingContextInterface $renderingContext)
     {
         $objectManager = $renderingContext->getObjectManager();
-        /** @var Context $securityContext */
+        /** @var ?Context $securityContext */
         $securityContext = $objectManager->get(Context::class);
 
         if ($securityContext !== null && !$securityContext->canBeInitialized()) {
             return false;
         }
+        $privilegeTarget = $arguments['privilegeTarget'] ?? null;
+        if (!is_string($privilegeTarget)) {
+            throw new \Exception('Missing privilegeTarget argument.', 1743848049);
+        }
         $privilegeManager = static::getPrivilegeManager($renderingContext);
-        return $privilegeManager->isPrivilegeTargetGranted($arguments['privilegeTarget'], $arguments['parameters'] ?? []);
+        return $privilegeManager->isPrivilegeTargetGranted($privilegeTarget, $arguments['parameters'] ?? []);
     }
 
     /**
-     * @param RenderingContext $renderingContext
      * @return PrivilegeManagerInterface
      */
-    protected static function getPrivilegeManager(RenderingContext $renderingContext)
+    protected static function getPrivilegeManager(FlowAwareRenderingContextInterface $renderingContext)
     {
         $objectManager = $renderingContext->getObjectManager();
         return $objectManager->get(PrivilegeManagerInterface::class);
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/Security/IfAuthenticatedViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/Security/IfAuthenticatedViewHelper.php
index a7a78ae4b9..f7f6c6cb1f 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/Security/IfAuthenticatedViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/Security/IfAuthenticatedViewHelper.php
@@ -66,7 +66,7 @@ public function render()
     }
 
     /**
-     * @param null $arguments
+     * @param array<string,mixed>|null $arguments
      * @param FlowAwareRenderingContextInterface&RenderingContextInterface $renderingContext
      * @return bool
      */
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/Security/IfHasRoleViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/Security/IfHasRoleViewHelper.php
index 9be411ea51..b5669429e4 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/Security/IfHasRoleViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/Security/IfHasRoleViewHelper.php
@@ -78,6 +78,7 @@ class IfHasRoleViewHelper extends AbstractConditionViewHelper
 {
     /**
      * Initializes the "then" and "else" arguments
+     * @return void
      */
     public function initializeArguments()
     {
@@ -104,7 +105,7 @@ public function render()
     }
 
     /**
-     * @param array|null $arguments
+     * @param array<string,mixed>|null $arguments
      * @param FlowAwareRenderingContextInterface&RenderingContextInterface $renderingContext
      * @return boolean
      */
@@ -120,8 +121,8 @@ protected static function evaluateCondition($arguments, RenderingContextInterfac
             return false;
         }
 
-        $role = $arguments['role'];
-        $account = $arguments['account'];
+        $role = $arguments['role'] ?? null;
+        $account = $arguments['account'] ?? null;
         $packageKey = isset($arguments['packageKey']) ? $arguments['packageKey'] : $renderingContext->getControllerContext()->getRequest()->getControllerPackageKey();
 
         if (is_string($role)) {
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/TranslateViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/TranslateViewHelper.php
index c4c0d06f0b..d15b0f6a95 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/TranslateViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/TranslateViewHelper.php
@@ -15,7 +15,6 @@
 use Neos\Flow\I18n\Exception\InvalidLocaleIdentifierException;
 use Neos\Flow\I18n\Locale;
 use Neos\Flow\I18n\Translator;
-use Neos\Flow\Mvc\ActionRequest;
 use Neos\FluidAdaptor\Core\ViewHelper;
 use Neos\FluidAdaptor\Core\ViewHelper\Exception as ViewHelperException;
 
@@ -122,9 +121,7 @@ public function render()
         }
         if ($package === null) {
             $request = $this->renderingContext->getControllerContext()->getRequest();
-            if ($request instanceof ActionRequest) {
-                $package = $request->getControllerPackageKey();
-            }
+            $package = $request->getControllerPackageKey();
             if (empty($package)) {
                 throw new ViewHelperException(
                     'The current package key can\'t be resolved. Make sure to initialize the Fluid view with a proper ActionRequest and/or specify the "package" argument when using the f:translate ViewHelper',
@@ -150,6 +147,7 @@ public function render()
 
     /**
      * @param Translator $translator
+     * @return void
      */
     public function injectTranslator(Translator $translator)
     {
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/Uri/ResourceViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/Uri/ResourceViewHelper.php
index 6254572c13..7caf99eec5 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/Uri/ResourceViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/Uri/ResourceViewHelper.php
@@ -100,7 +100,7 @@ public function render()
     }
 
     /**
-     * @param array $arguments
+     * @param array<string,mixed> $arguments
      * @param \Closure $renderChildrenClosure
      * @param FlowAwareRenderingContextInterface&RenderingContextInterface $renderingContext
      * @return string
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/Validation/IfHasErrorsViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/Validation/IfHasErrorsViewHelper.php
index 3efab8366c..40f593e560 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/Validation/IfHasErrorsViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/Validation/IfHasErrorsViewHelper.php
@@ -70,7 +70,7 @@ public function render()
     }
 
     /**
-     * @param null $arguments
+     * @param array<mixed> $arguments
      * @param FlowAwareRenderingContextInterface&RenderingContextInterface $renderingContext
      * @return boolean
      */
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/Widget/Controller/AutocompleteController.php b/Neos.FluidAdaptor/Classes/ViewHelpers/Widget/Controller/AutocompleteController.php
index 9dd40909a6..a9468b212a 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/Widget/Controller/AutocompleteController.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/Widget/Controller/AutocompleteController.php
@@ -21,7 +21,7 @@
 class AutocompleteController extends AbstractWidgetController
 {
     /**
-     * @var array
+     * @var array<string,mixed>
      */
     protected $configuration = ['limit' => 10];
 
@@ -82,6 +82,6 @@ public function autocompleteAction($term)
                 'value' => $val
             ];
         }
-        return json_encode($output);
+        return json_encode($output, JSON_THROW_ON_ERROR);
     }
 }
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/Widget/Controller/PaginateController.php b/Neos.FluidAdaptor/Classes/ViewHelpers/Widget/Controller/PaginateController.php
index 1778c2c0a1..535ffe094d 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/Widget/Controller/PaginateController.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/Widget/Controller/PaginateController.php
@@ -26,7 +26,7 @@ class PaginateController extends AbstractWidgetController
     protected $objects;
 
     /**
-     * @var array
+     * @var array<string,mixed>
      */
     protected $configuration = ['itemsPerPage' => 10, 'insertAbove' => false, 'insertBelow' => true, 'maximumNumberOfLinks' => 99];
 
@@ -56,12 +56,12 @@ class PaginateController extends AbstractWidgetController
     protected $numberOfPages = 1;
 
     /**
-     * @var float
+     * @var integer
      */
     protected $displayRangeStart;
 
     /**
-     * @var float
+     * @var integer
      */
     protected $displayRangeEnd;
 
@@ -117,22 +117,30 @@ protected function calculateDisplayRange()
             $maximumNumberOfLinks = $this->numberOfPages;
         }
         $delta = floor($maximumNumberOfLinks / 2);
-        $this->displayRangeStart = $this->currentPage - $delta;
-        $this->displayRangeEnd = $this->currentPage + $delta + ($maximumNumberOfLinks % 2 === 0 ? 1 : 0);
-        if ($this->displayRangeStart < 1) {
-            $this->displayRangeEnd -= $this->displayRangeStart - 1;
+        $displayRangeStart = $this->currentPage - $delta;
+        $displayRangeEnd = $this->currentPage + $delta + ($maximumNumberOfLinks % 2 === 0 ? 1 : 0);
+        if ($displayRangeStart < 1) {
+            $displayRangeEnd -= $displayRangeStart - 1;
         }
-        if ($this->displayRangeEnd > $this->numberOfPages) {
-            $this->displayRangeStart -= ($this->displayRangeEnd - $this->numberOfPages);
+        if ($displayRangeEnd > $this->numberOfPages) {
+            $displayRangeStart -= ($displayRangeEnd - $this->numberOfPages);
         }
-        $this->displayRangeStart = (integer)max($this->displayRangeStart, 1);
-        $this->displayRangeEnd = (integer)min($this->displayRangeEnd, $this->numberOfPages);
+        $this->displayRangeStart = (integer)max($displayRangeStart, 1);
+        $this->displayRangeEnd = (integer)min($displayRangeEnd, $this->numberOfPages);
     }
 
     /**
-     * Returns an array with the keys "pages", "current", "numberOfPages", "nextPage" & "previousPage"
-     *
-     * @return array
+     * @return array{
+     *     pages: list<array{number: int, isCurrent: bool}>,
+     *     current: int,
+     *     numberOfPages: int,
+     *     displayRangeStart: float,
+     *     displayRangeEnd: float,
+     *     hasLessPages: bool,
+     *     hasMorePages: bool,
+     *     nextPage?: int,
+     *     previousPage?: int,
+     * }
      */
     protected function buildPagination()
     {
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/Widget/LinkViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/Widget/LinkViewHelper.php
index 55de2b8c53..5a6800624a 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/Widget/LinkViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/Widget/LinkViewHelper.php
@@ -120,7 +120,7 @@ protected function getAjaxUri(): string
         } else {
             $arguments['__widgetId'] = $widgetContext->getAjaxWidgetIdentifier();
         }
-        return '?' . http_build_query($arguments, null, '&');
+        return '?' . http_build_query(data: $arguments, arg_separator: '&');
     }
 
     /**
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/Widget/UriViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/Widget/UriViewHelper.php
index f96c6702e2..a57cb01bcf 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/Widget/UriViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/Widget/UriViewHelper.php
@@ -104,7 +104,7 @@ protected function getAjaxUri(): string
         } else {
             $arguments['__widgetId'] = $widgetContext->getAjaxWidgetIdentifier();
         }
-        return '?' . http_build_query($arguments, null, '&');
+        return '?' . http_build_query(data: $arguments, arg_separator: '&');
     }
 
     /**
diff --git a/Neos.Http.Factories/Classes/FlowUploadedFile.php b/Neos.Http.Factories/Classes/FlowUploadedFile.php
index e9f5e296cb..04ca49a8db 100644
--- a/Neos.Http.Factories/Classes/FlowUploadedFile.php
+++ b/Neos.Http.Factories/Classes/FlowUploadedFile.php
@@ -14,7 +14,7 @@ class FlowUploadedFile extends UploadedFile
      * This is either the persistent identifier of a previously submitted resource file
      * or an array with the "__identity" key set to the persistent identifier.
      *
-     * @var array|string
+     * @var array{__identity: string}|string
      */
     protected $originallySubmittedResource;
 
@@ -27,7 +27,7 @@ class FlowUploadedFile extends UploadedFile
      * This is either the persistent identifier of a previously submitted resource file
      * or an array with the "__identity" key set to the persistent identifier.
      *
-     * @return array|string
+     * @return array{__identity: string}|string
      */
     public function getOriginallySubmittedResource()
     {
@@ -40,7 +40,8 @@ public function getOriginallySubmittedResource()
      * This is either the persistent identifier of a previously submitted resource file
      * or an array with the "__identity" key set to the persistent identifier.
      *
-     * @param array|string $originallySubmittedResource
+     * @param array{__identity: string}|string $originallySubmittedResource
+     * @return void
      */
     public function setOriginallySubmittedResource($originallySubmittedResource)
     {
@@ -57,6 +58,7 @@ public function getCollectionName()
 
     /**
      * @param string $collectionName
+     * @return void
      */
     public function setCollectionName($collectionName)
     {
diff --git a/Neos.Http.Factories/Classes/RequestFactoryTrait.php b/Neos.Http.Factories/Classes/RequestFactoryTrait.php
index 364bfb21de..b840389da0 100644
--- a/Neos.Http.Factories/Classes/RequestFactoryTrait.php
+++ b/Neos.Http.Factories/Classes/RequestFactoryTrait.php
@@ -13,6 +13,7 @@
 trait RequestFactoryTrait
 {
     /**
+     * @param non-empty-string $method
      * @inheritDoc
      */
     public function createRequest(string $method, $uri): RequestInterface
diff --git a/Neos.Http.Factories/Classes/ServerRequestFactoryTrait.php b/Neos.Http.Factories/Classes/ServerRequestFactoryTrait.php
index b4be972e24..1208f5569f 100644
--- a/Neos.Http.Factories/Classes/ServerRequestFactoryTrait.php
+++ b/Neos.Http.Factories/Classes/ServerRequestFactoryTrait.php
@@ -56,6 +56,7 @@ public function __construct(
 
     /**
      * @inheritDoc
+     * @param array<mixed> $serverParams
      */
     public function createServerRequest(string $method, $uri, array $serverParams = []): ServerRequestInterface
     {
diff --git a/Neos.Http.Factories/Classes/StreamFactoryTrait.php b/Neos.Http.Factories/Classes/StreamFactoryTrait.php
index 6c79adcc84..f8201880bc 100644
--- a/Neos.Http.Factories/Classes/StreamFactoryTrait.php
+++ b/Neos.Http.Factories/Classes/StreamFactoryTrait.php
@@ -18,6 +18,9 @@ trait StreamFactoryTrait
     public function createStream(string $content = ''): StreamInterface
     {
         $fileHandle = fopen('php://temp', 'r+');
+        if (!is_resource($fileHandle)) {
+            throw new \Exception('unable to open php://temp', 1743846274);
+        }
         fwrite($fileHandle, $content);
         rewind($fileHandle);
 
@@ -30,11 +33,15 @@ public function createStream(string $content = ''): StreamInterface
     public function createStreamFromFile(string $filename, string $mode = 'r'): StreamInterface
     {
         $fileHandle = fopen($filename, $mode);
+        if (!is_resource($fileHandle)) {
+            throw new \Exception('unable to open ' . $filename, 1743846243);
+        }
         return $this->createStreamFromResource($fileHandle);
     }
 
     /**
      * @inheritDoc
+     * @param resource $resource
      */
     public function createStreamFromResource($resource): StreamInterface
     {
diff --git a/Neos.Kickstarter/Classes/Command/KickstartCommandController.php b/Neos.Kickstarter/Classes/Command/KickstartCommandController.php
index 246b927c0c..7150c5ae49 100644
--- a/Neos.Kickstarter/Classes/Command/KickstartCommandController.php
+++ b/Neos.Kickstarter/Classes/Command/KickstartCommandController.php
@@ -47,6 +47,7 @@ class KickstartCommandController extends CommandController
      *
      * @param string $packageKey The package key, for example "MyCompany.MyPackageName"
      * @param string $packageType Optional package type, e.g. "neos-plugin"
+     * @return void
      * @see neos.flow:package:create
      */
     public function packageCommand($packageKey, $packageType = PackageInterface::DEFAULT_COMPOSER_TYPE)
@@ -99,6 +100,7 @@ public function packageCommand($packageKey, $packageType = PackageInterface::DEF
      * @param boolean $generateFusion If Fusion templates should be generated instead of Fluid.
      * @param boolean $generateRelated Also create the mentioned package, related model and repository if necessary.
      * @param boolean $force Overwrite any existing controller or template code. Regardless of this flag, the package, model and repository will never be overwritten.
+     * @return void
      * @see neos.kickstarter:kickstart:commandcontroller
      */
     public function actionControllerCommand($packageKey, $controllerName, $generateActions = false, $generateTemplates = true, $generateFusion = false, $generateRelated = false, $force = false)
@@ -193,6 +195,7 @@ public function actionControllerCommand($packageKey, $controllerName, $generateA
      * @param string $packageKey The package key of the package for the new controller
      * @param string $controllerName The name for the new controller. This may also be a comma separated list of controller names.
      * @param boolean $force Overwrite any existing controller.
+     * @return void
      * @see neos.kickstarter:kickstart:actioncontroller
      */
     public function commandControllerCommand($packageKey, $controllerName, $force = false)
@@ -220,6 +223,7 @@ public function commandControllerCommand($packageKey, $controllerName, $force =
      * @param string $packageKey The package key of the package for the domain model
      * @param string $modelName The name of the new domain model class
      * @param boolean $force Overwrite any existing model.
+     * @return void
      * @see neos.kickstarter:kickstart:repository
      */
     public function modelCommand($packageKey, $modelName, $force = false)
@@ -262,6 +266,7 @@ public function modelCommand($packageKey, $modelName, $force = false)
      * @param string $packageKey The package key
      * @param string $modelName The name of the domain model class
      * @param boolean $force Overwrite any existing repository.
+     * @return void
      * @see neos.kickstarter:kickstart:model
      */
     public function repositoryCommand($packageKey, $modelName, $force = false)
@@ -282,6 +287,7 @@ public function repositoryCommand($packageKey, $modelName, $force = false)
      * Generates a documentation skeleton for the given package.
      *
      * @param string $packageKey The package key of the package for the documentation
+     * @return void
      */
     public function documentationCommand($packageKey)
     {
@@ -303,7 +309,7 @@ public function documentationCommand($packageKey)
      *
      * @param string $packageKey The package key of the package for the translation
      * @param string $sourceLanguageKey The language key of the default language
-     * @param array $targetLanguageKeys Comma separated language keys for the target translations
+     * @param array<string> $targetLanguageKeys Comma separated language keys for the target translations
      * @return void
      */
     public function translationCommand($packageKey, $sourceLanguageKey, array $targetLanguageKeys = [])
@@ -337,6 +343,7 @@ protected function validatePackageKey($packageKey)
      * Check the given model name to be not one of the reserved words of PHP.
      *
      * @param string $modelName
+     * @return void
      * @see http://www.php.net/manual/en/reserved.keywords.php
      */
     protected function validateModelName($modelName)
diff --git a/Neos.Kickstarter/Classes/Service/GeneratorService.php b/Neos.Kickstarter/Classes/Service/GeneratorService.php
index e872b5f181..7ff7b55ba2 100644
--- a/Neos.Kickstarter/Classes/Service/GeneratorService.php
+++ b/Neos.Kickstarter/Classes/Service/GeneratorService.php
@@ -51,9 +51,9 @@ class GeneratorService
     protected $reflectionService;
 
     /**
-     * @var array
+     * @var array<int,string>
      */
-    protected $generatedFiles = [];
+    protected array $generatedFiles = [];
 
     /**
      * Generate a controller with the given name for the given package
@@ -63,7 +63,7 @@ class GeneratorService
      * @param string $controllerName The name of the new controller
      * @param boolean $fusionView If the controller should default to a FusionView
      * @param boolean $overwrite Overwrite any existing files?
-     * @return array An array of generated filenames
+     * @return array<int,string> An array of generated filenames
      */
     public function generateActionController($packageKey, $subpackage, $controllerName, $fusionView = false, $overwrite = false)
     {
@@ -102,7 +102,7 @@ public function generateActionController($packageKey, $subpackage, $controllerNa
      * @param string $controllerName The name of the new controller
      * @param boolean $fusionView If the controller should default to a FusionView
      * @param boolean $overwrite Overwrite any existing files?
-     * @return array An array of generated filenames
+     * @return array<int,string> An array of generated filenames
      */
     public function generateCrudController($packageKey, $subpackage, $controllerName, $fusionView = false, $overwrite = false)
     {
@@ -143,7 +143,7 @@ public function generateCrudController($packageKey, $subpackage, $controllerName
      * @param string $packageKey The package key of the controller's package
      * @param string $controllerName The name of the new controller
      * @param boolean $overwrite Overwrite any existing files?
-     * @return array An array of generated filenames
+     * @return array<int,string> An array of generated filenames
      */
     public function generateCommandController($packageKey, $controllerName, $overwrite = false)
     {
@@ -179,7 +179,7 @@ public function generateCommandController($packageKey, $controllerName, $overwri
      * @param string $viewName The name of the view
      * @param string $templateName The name of the view
      * @param boolean $overwrite Overwrite any existing files?
-     * @return array An array of generated filenames
+     * @return array<int,string> An array of generated filenames
      */
     public function generateView($packageKey, $subpackage, $controllerName, $viewName, $templateName, $overwrite = false)
     {
@@ -199,7 +199,9 @@ public function generateView($packageKey, $subpackage, $controllerName, $viewNam
         $contextVariables['modelFullClassName'] = '\\' . trim($baseNamespace, '\\') . ($subpackage != '' ? '\\' . $subpackage : '') . '\Domain\Model\\' . $controllerName;
         $contextVariables['modelClassName'] = ucfirst($contextVariables['modelName']);
 
-        $modelClassSchema = $this->reflectionService->getClassSchema($contextVariables['modelFullClassName']);
+        $modelClassSchema = class_exists($contextVariables['modelFullClassName'])
+            ? $this->reflectionService->getClassSchema($contextVariables['modelFullClassName'])
+            : null;
         if ($modelClassSchema !== null) {
             $contextVariables['properties'] = $modelClassSchema->getProperties();
             if (isset($contextVariables['properties']['Persistence_Object_Identifier'])) {
@@ -229,7 +231,7 @@ public function generateView($packageKey, $subpackage, $controllerName, $viewNam
      * @param string $packageKey The package key of the controller's package
      * @param string $layoutName The name of the layout
      * @param boolean $overwrite Overwrite any existing files?
-     * @return array An array of generated filenames
+     * @return array<int,string> An array of generated filenames
      */
     public function generateLayout($packageKey, $layoutName, $overwrite = false)
     {
@@ -261,7 +263,7 @@ public function generateLayout($packageKey, $layoutName, $overwrite = false)
      * @param string $viewName The name of the view
      * @param string $templateName The name of the view
      * @param boolean $overwrite Overwrite any existing files?
-     * @return array An array of generated filenames
+     * @return array<int,string> An array of generated filenames
      */
     public function generateFusion(string $packageKey, string $subpackage, string $controllerName, string $viewName, string $templateName, bool $overwrite = false): array
     {
@@ -281,7 +283,9 @@ public function generateFusion(string $packageKey, string $subpackage, string $c
         $contextVariables['modelFullClassName'] = '\\' . trim($baseNamespace, '\\') . ($subpackage != '' ? '\\' . $subpackage : '') . '\Domain\Model\\' . $controllerName;
         $contextVariables['modelClassName'] = ucfirst($contextVariables['modelName']);
 
-        $modelClassSchema = $this->reflectionService->getClassSchema($contextVariables['modelFullClassName']);
+        $modelClassSchema = class_exists($contextVariables['modelFullClassName'])
+            ? $this->reflectionService->getClassSchema($contextVariables['modelFullClassName'])
+            : null;
         if ($modelClassSchema !== null) {
             $contextVariables['properties'] = $modelClassSchema->getProperties();
             if (isset($contextVariables['properties']['Persistence_Object_Identifier'])) {
@@ -311,7 +315,7 @@ public function generateFusion(string $packageKey, string $subpackage, string $c
      * @param string $packageKey The package key of the controller's package
      * @param string $layoutName The name of the layout
      * @param boolean $overwrite Overwrite any existing files?
-     * @return array An array of generated filenames
+     * @return array<int,string> An array of generated filenames
      */
     public function generatePrototype(string $packageKey, string $layoutName, bool $overwrite = false): array
     {
@@ -340,9 +344,9 @@ public function generatePrototype(string $packageKey, string $layoutName, bool $
      *
      * @param string $packageKey The package key of the controller's package
      * @param string $modelName The name of the new model
-     * @param array $fieldDefinitions The field definitions
+     * @param array<mixed> $fieldDefinitions The field definitions
      * @param boolean $overwrite Overwrite any existing files?
-     * @return array An array of generated filenames
+     * @return array<int,string> An array of generated filenames
      */
     public function generateModel($packageKey, $modelName, array $fieldDefinitions, $overwrite = false)
     {
@@ -378,7 +382,7 @@ public function generateModel($packageKey, $modelName, array $fieldDefinitions,
      * @param string $packageKey The package key of the controller's package
      * @param string $modelName The name of the new model fpr which to generate the test
      * @param boolean $overwrite Overwrite any existing files?
-     * @return array An array of generated filenames
+     * @return array<int,string> An array of generated filenames
      */
     public function generateTestsForModel($packageKey, $modelName, $overwrite = false)
     {
@@ -411,7 +415,7 @@ public function generateTestsForModel($packageKey, $modelName, $overwrite = fals
      * @param string $packageKey The package key
      * @param string $modelName The name of the model
      * @param boolean $overwrite Overwrite any existing files?
-     * @return array An array of generated filenames
+     * @return array<int,string> An array of generated filenames
      */
     public function generateRepository($packageKey, $modelName, $overwrite = false)
     {
@@ -443,7 +447,7 @@ public function generateRepository($packageKey, $modelName, $overwrite = false)
      * Generate a documentation skeleton for the package key
      *
      * @param string $packageKey The package key
-     * @return array An array of generated filenames
+     * @return array<int,string> An array of generated filenames
      */
     public function generateDocumentation($packageKey)
     {
@@ -459,7 +463,7 @@ public function generateDocumentation($packageKey)
         $templatePathAndFilename = 'resource://Neos.Kickstarter/Private/Generator/Documentation/Makefile';
         $fileContent = file_get_contents($templatePathAndFilename);
         $targetPathAndFilename = $documentationPath . '/Makefile';
-        $this->generateFile($targetPathAndFilename, $fileContent);
+        $this->generateFile($targetPathAndFilename, $fileContent ?: '');
 
         $templatePathAndFilename = 'resource://Neos.Kickstarter/Private/Generator/Documentation/index.rst';
         $fileContent = $this->renderTemplate($templatePathAndFilename, $contextVariables);
@@ -481,8 +485,8 @@ public function generateDocumentation($packageKey)
      *
      * @param string $packageKey
      * @param string $sourceLanguageKey
-     * @param array $targetLanguageKeys
-     * @return array An array of generated filenames
+     * @param array<string> $targetLanguageKeys
+     * @return array<int,string> An array of generated filenames
      */
     public function generateTranslation($packageKey, $sourceLanguageKey, array $targetLanguageKeys = [])
     {
@@ -516,9 +520,9 @@ public function generateTranslation($packageKey, $sourceLanguageKey, array $targ
     /**
      * Normalize types and prefix types with namespaces
      *
-     * @param array $fieldDefinitions The field definitions
+     * @param array<mixed> $fieldDefinitions The field definitions
      * @param string $namespace The namespace
-     * @return array The normalized and type converted field definitions
+     * @return array<mixed> The normalized and type converted field definitions
      */
     protected function normalizeFieldDefinitions(array $fieldDefinitions, $namespace = '')
     {
@@ -574,7 +578,7 @@ protected function generateFile($targetPathAndFilename, $fileContent, $force = f
      * Render the given template file with the given variables
      *
      * @param string $templatePathAndFilename
-     * @param array $contextVariables
+     * @param array<mixed> $contextVariables
      * @return string
      * @throws \Neos\FluidAdaptor\Core\Exception
      */
@@ -588,7 +592,7 @@ protected function renderTemplate($templatePathAndFilename, array $contextVariab
 
     /**
      * @param PackageInterface $package
-     * @return array
+     * @return array<mixed>
      */
     protected function getPrimaryNamespaceAndEntryPath(PackageInterface $package)
     {
diff --git a/Neos.Kickstarter/Classes/Utility/Inflector.php b/Neos.Kickstarter/Classes/Utility/Inflector.php
index ed402234f7..49fa0eb222 100644
--- a/Neos.Kickstarter/Classes/Utility/Inflector.php
+++ b/Neos.Kickstarter/Classes/Utility/Inflector.php
@@ -56,6 +56,6 @@ public function humanizeCamelCase($camelCased, $lowercase = false)
      */
     protected function spacify($camelCased, $glue = ' ')
     {
-        return preg_replace('/([a-z0-9])([A-Z])/', '$1' . $glue . '$2', $camelCased);
+        return preg_replace('/([a-z0-9])([A-Z])/', '$1' . $glue . '$2', $camelCased) ?: '';
     }
 }
diff --git a/Neos.Utility.Arrays/Classes/Arrays.php b/Neos.Utility.Arrays/Classes/Arrays.php
index 71a44f2aeb..910ff7e032 100644
--- a/Neos.Utility.Arrays/Classes/Arrays.php
+++ b/Neos.Utility.Arrays/Classes/Arrays.php
@@ -22,9 +22,9 @@ abstract class Arrays
      * Explodes a $string delimited by $delimiter and passes each item in the array through intval().
      * Corresponds to explode(), but with conversion to integers for all values.
      *
-     * @param string $delimiter Delimiter string to explode with
+     * @param non-empty-string $delimiter Delimiter string to explode with
      * @param string $string The string to explode
-     * @return array Exploded values, all converted to integers
+     * @return array<mixed> Exploded values, all converted to integers
      */
     public static function integerExplode(string $delimiter, string $string): array
     {
@@ -41,10 +41,10 @@ public static function integerExplode(string $delimiter, string $string): array
      * Explodes a string and trims all values for whitespace in the ends.
      * If $onlyNonEmptyValues is set, then all blank ('') values are removed.
      *
-     * @param string $delimiter Delimiter string to explode with
+     * @param non-empty-string $delimiter Delimiter string to explode with
      * @param string $string The string to explode
      * @param boolean $onlyNonEmptyValues If disabled, even empty values (='') will be set in output
-     * @return array Exploded values
+     * @return array<mixed> Exploded values
      */
     public static function trimExplode(string $delimiter, string $string, bool $onlyNonEmptyValues = true): array
     {
@@ -64,11 +64,11 @@ public static function trimExplode(string $delimiter, string $string, bool $only
      * in the first array ($firstArray) with the values of the second array ($secondArray) in case of identical keys,
      * ie. keeping the values of the second.
      *
-     * @param array $firstArray First array
-     * @param array $secondArray Second array, overruling the first array
+     * @param array<mixed> $firstArray First array
+     * @param array<mixed> $secondArray Second array, overruling the first array
      * @param boolean $dontAddNewKeys If set, keys that are NOT found in $firstArray (first array) will not be set. Thus only existing value can/will be overruled from second array.
      * @param boolean $emptyValuesOverride If set (which is the default), values from $secondArray will overrule if they are empty (according to PHP's empty() function)
-     * @return array Resulting array where $secondArray values has overruled $firstArray values
+     * @return array<mixed> Resulting array where $secondArray values has overruled $firstArray values
      */
     public static function arrayMergeRecursiveOverrule(array $firstArray, array $secondArray, bool $dontAddNewKeys = false, bool $emptyValuesOverride = true): array
     {
@@ -109,13 +109,13 @@ public static function arrayMergeRecursiveOverrule(array $firstArray, array $sec
      * Merges two arrays recursively and "binary safe" (integer keys are overridden as well), overruling similar values in the first array ($firstArray) with the values of the second array ($secondArray)
      * In case of identical keys, ie. keeping the values of the second. The given $toArray closure will be used if one of the two array keys contains an array and the other not. It should return an array.
      *
-     * @param array $firstArray First array
-     * @param array $secondArray Second array, overruling the first array
+     * @param array<mixed> $firstArray First array
+     * @param array<mixed> $secondArray Second array, overruling the first array
      * @param \Closure $toArray The given callable will get a value that is not an array and has to return an array.
      *                          This is to allow custom merging of simple types with (sub) arrays
      * @param \Closure|null $overrideFirst The given callable will determine whether the value of the first array should be overridden.
      *                                     It should have the following signature $callable($key, ?array $firstValue = null, ?array $secondValue = null): bool
-     * @return array Resulting array where $secondArray values has overruled $firstArray values
+     * @return array<mixed> Resulting array where $secondArray values has overruled $firstArray values
      */
     public static function arrayMergeRecursiveOverruleWithCallback(array $firstArray, array $secondArray, \Closure $toArray, ?\Closure $overrideFirst = null): array
     {
@@ -157,8 +157,7 @@ public static function arrayMergeRecursiveOverruleWithCallback(array $firstArray
     /**
      * Returns true if the given array contains elements of varying types
      *
-     * @param array $array
-     * @return boolean
+     * @param array<mixed> $array
      */
     public static function containsMultipleTypes(array $array): bool
     {
@@ -179,12 +178,13 @@ public static function containsMultipleTypes(array $array): bool
      * Replacement for array_reduce that allows any type for $initial (instead
      * of only integer)
      *
-     * @param array $array the array to reduce
-     * @param string $function the reduce function with the same order of parameters as in the native array_reduce (i.e. accumulator first, then current array element)
+     * @phpstan-param callable-string $function
+     * @param array<mixed> $array the array to reduce
+     * @param callable $function the reduce function with the same order of parameters as in the native array_reduce (i.e. accumulator first, then current array element)
      * @param mixed $initial the initial accumulator value
      * @return mixed
      */
-    public static function array_reduce(array $array, string $function, $initial = null)
+    public static function array_reduce(array $array, callable $function, $initial = null)
     {
         $accumulator = $initial;
         foreach ($array as $value) {
@@ -196,8 +196,8 @@ public static function array_reduce(array $array, string $function, $initial = n
     /**
      * Returns the value of a nested array by following the specifed path.
      *
-     * @param array $array The array to traverse
-     * @param array|string $path The path to follow. Either a simple array of keys or a string in the format 'foo.bar.baz'
+     * @param array<mixed> $array The array to traverse
+     * @param array<mixed>|string $path The path to follow. Either a simple array of keys or a string in the format 'foo.bar.baz'
      * @return mixed The value found, NULL if the path didn't exist (note there is no way to distinguish between a found NULL value and "path not found")
      */
     public static function getValueByPath(array $array, array|string $path): mixed
@@ -222,8 +222,8 @@ public static function getValueByPath(array $array, array|string $path): mixed
      * See {@see ValueAccessor}
      *
      * @internal experimental feature, not stable API
-     * @param array $array The array to traverse
-     * @param array|string $path The path to follow. Either a simple array of keys or a string in the format 'foo.bar.baz'
+     * @param array<mixed> $array The array to traverse
+     * @param array<mixed>|string $path The path to follow. Either a simple array of keys or a string in the format 'foo.bar.baz'
      * @return ValueAccessor
      */
     public static function getAccessorByPath(array $array, array|string $path): ValueAccessor
@@ -235,16 +235,17 @@ public static function getAccessorByPath(array $array, array|string $path): Valu
     /**
      * Sets the given value in a nested array or object by following the specified path.
      *
-     * @param array|\ArrayAccess $subject The array or ArrayAccess instance to work on
-     * @param array|string $path The path to follow. Either a simple array of keys or a string in the format 'foo.bar.baz'
+     * @param array<mixed>|\ArrayAccess<int|string, mixed> $subject The array or ArrayAccess instance to work on
+     * @param array<mixed>|string $path The path to follow. Either a simple array of keys or a string in the format 'foo.bar.baz'
      * @param mixed $value The value to set
-     * @return array|\ArrayAccess The modified array or object
+     * @return array<mixed>|\ArrayAccess<int|string, mixed> The modified array or object
      * @throws \InvalidArgumentException
      */
     public static function setValueByPath($subject, $path, $value)
     {
+        /** @phpstan-ignore booleanAnd.alwaysFalse (annotations may be wrong) */
         if (!is_array($subject) && !($subject instanceof \ArrayAccess)) {
-            throw new \InvalidArgumentException('setValueByPath() expects $subject to be array or an object implementing \ArrayAccess, "' . (is_object($subject) ? get_class($subject) : gettype($subject)) . '" given.', 1306424308);
+            throw new \InvalidArgumentException('setValueByPath() expects $subject to be array or an object implementing \ArrayAccess, "' . get_debug_type($subject) . '" given.', 1306424308);
         }
         if (is_string($path)) {
             $path = explode('.', $path);
@@ -266,9 +267,9 @@ public static function setValueByPath($subject, $path, $value)
     /**
      * Unsets an element/part of a nested array by following the specified path.
      *
-     * @param array $array The array
-     * @param array|string $path The path to follow. Either a simple array of keys or a string in the format 'foo.bar.baz'
-     * @return array The modified array
+     * @param array<mixed> $array The array
+     * @param array<mixed>|string $path The path to follow. Either a simple array of keys or a string in the format 'foo.bar.baz'
+     * @return array<mixed> The modified array
      * @throws \InvalidArgumentException
      */
     public static function unsetValueByPath(array $array, $path): array
@@ -293,7 +294,7 @@ public static function unsetValueByPath(array $array, $path): array
     /**
      * Sorts multidimensional arrays by recursively calling ksort on its elements.
      *
-     * @param array $array the array to sort
+     * @param array<mixed> $array the array to sort
      * @param integer $sortFlags may be used to modify the sorting behavior using these values (see http://www.php.net/manual/en/function.sort.php)
      * @return boolean true on success, false on failure
      * @see asort()
@@ -314,7 +315,7 @@ public static function sortKeysRecursively(array &$array, int $sortFlags = \SORT
      * Recursively convert an object hierarchy into an associative array.
      *
      * @param mixed $subject An object or array of objects
-     * @return array The subject represented as an array
+     * @return array<mixed> The subject represented as an array
      * @throws \InvalidArgumentException
      */
     public static function convertObjectToArray($subject): array
@@ -336,8 +337,8 @@ public static function convertObjectToArray($subject): array
     /**
      * Recursively removes empty array elements.
      *
-     * @param array $array
-     * @return array the modified array
+     * @param array<mixed> $array
+     * @return array<mixed> the modified array
      */
     public static function removeEmptyElementsRecursively(array $array): array
     {
diff --git a/Neos.Utility.Arrays/Classes/PositionalArraySorter.php b/Neos.Utility.Arrays/Classes/PositionalArraySorter.php
index e900ddd58d..fd05be60ed 100644
--- a/Neos.Utility.Arrays/Classes/PositionalArraySorter.php
+++ b/Neos.Utility.Arrays/Classes/PositionalArraySorter.php
@@ -44,18 +44,33 @@
  */
 final class PositionalArraySorter
 {
+    /**
+     * @var array<mixed>
+     */
     private array $startKeys;
 
+    /**
+     * @var array<mixed>
+     */
     private array $middleKeys;
 
+    /**
+     * @var array<mixed>
+     */
     private array $endKeys;
 
+    /**
+     * @var array<mixed>
+     */
     private array $beforeKeys;
 
+    /**
+     * @var array<mixed>
+     */
     private array $afterKeys;
 
     /**
-     * @param array $subject The source array to sort
+     * @param array<mixed> $subject The source array to sort
      * @param string $positionPropertyPath optional property path to the string that contains the position
      * @param bool $removeNullValues if set to TRUE (default), null-values of the subject are removed
      */
@@ -69,7 +84,7 @@ public function __construct(
     /**
      * Returns a sorted copy of the subject array
      *
-     * @return array
+     * @return array<mixed>
      * @throws Exception\InvalidPositionException
      */
     public function toArray(): array
@@ -87,7 +102,7 @@ public function toArray(): array
      *
      * TODO Detect circles in after / before dependencies (#52185)
      *
-     * @return array an ordered list of keys
+     * @return array<mixed> an ordered list of keys
      * @throws Exception\InvalidPositionException if the positional string has an unsupported format
      */
     public function getSortedKeys(): array
@@ -112,6 +127,8 @@ public function getSortedKeys(): array
      * Extracts all "middle" keys from $arrayKeysWithPosition. Those are all keys with a numeric position.
      * The result is a multidimensional arrays where the KEY of each array is a PRIORITY and the VALUE is an array of matching KEYS
      * This also removes matching keys from the given $arrayKeysWithPosition
+     *
+     * @param array<mixed> $arrayKeysWithPosition
      */
     private function extractMiddleKeys(array &$arrayKeysWithPosition): void
     {
@@ -130,6 +147,8 @@ private function extractMiddleKeys(array &$arrayKeysWithPosition): void
      * Extracts all "start" keys from $arrayKeysWithPosition. Those are all keys with a position starting with "start"
      * The result is a multidimensional arrays where the KEY of each array is a PRIORITY and the VALUE is an array of matching KEYS
      * This also removes matching keys from the given $arrayKeysWithPosition
+     *
+     * @param array<mixed> $arrayKeysWithPosition
      */
     private function extractStartKeys(array &$arrayKeysWithPosition): void
     {
@@ -152,6 +171,8 @@ private function extractStartKeys(array &$arrayKeysWithPosition): void
      * Extracts all "end" keys from $arrayKeysWithPosition. Those are all keys with a position starting with "end"
      * The result is a multidimensional arrays where the KEY of each array is a PRIORITY and the VALUE is an array of matching KEYS
      * This also removes matching keys from the given $arrayKeysWithPosition
+     *
+     * @param array<mixed> $arrayKeysWithPosition
      */
     private function extractEndKeys(array &$arrayKeysWithPosition): void
     {
@@ -174,6 +195,9 @@ private function extractEndKeys(array &$arrayKeysWithPosition): void
      * Extracts all "before" keys from $arrayKeysWithPosition. Those are all keys with a position starting with "before"
      * The result is a multidimensional arrays where the KEY of each array is a PRIORITY and the VALUE is an array of matching KEYS
      * This also removes matching keys from the given $arrayKeysWithPosition
+     *
+     * @param array<mixed> $arrayKeysWithPosition
+     * @param array<mixed> $existingKeys
      */
     private function extractBeforeKeys(array &$arrayKeysWithPosition, array $existingKeys): void
     {
@@ -201,6 +225,9 @@ private function extractBeforeKeys(array &$arrayKeysWithPosition, array $existin
      * Extracts all "after" keys from $arrayKeysWithPosition. Those are all keys with a position starting with "after"
      * The result is a multidimensional arrays where the KEY of each array is a PRIORITY and the VALUE is an array of matching KEYS
      * This also removes matching keys from the given $arrayKeysWithPosition
+     *
+     * @param array<mixed> $arrayKeysWithPosition
+     * @param array<mixed> $existingKeys
      */
     private function extractAfterKeys(array &$arrayKeysWithPosition, array $existingKeys): void
     {
@@ -228,7 +255,7 @@ private function extractAfterKeys(array &$arrayKeysWithPosition, array $existing
      * Collect the array keys inside $this->subject with each position meta-argument.
      * If there is no position but the array is numerically ordered, we use the array index as position.
      *
-     * @return array an associative array where each key of $subject has a position string assigned
+     * @return array<mixed> an associative array where each key of $subject has a position string assigned
      */
     private function collectArrayKeysAndPositions(): array
     {
@@ -253,6 +280,8 @@ private function collectArrayKeysAndPositions(): array
 
     /**
      * Flattens start-, middle-, end-, before- and afterKeys to a single dimension and merges them together to a single array
+     *
+     * @return array<mixed>
      */
     private function generateSortedKeysMap(): array
     {
diff --git a/Neos.Utility.Arrays/Classes/ValueAccessor.php b/Neos.Utility.Arrays/Classes/ValueAccessor.php
index 060ee0c8d7..54e0cd1179 100644
--- a/Neos.Utility.Arrays/Classes/ValueAccessor.php
+++ b/Neos.Utility.Arrays/Classes/ValueAccessor.php
@@ -47,6 +47,7 @@ public static function forValue(mixed $value): self
 
     /**
      * @internal You should use {@see ValueAccessor::forValue} instead
+     * @param array<mixed> $path
      */
     public static function forValueInPath(mixed $value, array|string $path): self
     {
@@ -97,6 +98,9 @@ public function classString(): string
         throw $this->createTypeError("is not a class-string");
     }
 
+    /**
+     * @return array<mixed>
+     */
     public function array(): array
     {
         if (is_array($this->value)) {
@@ -161,6 +165,9 @@ public function classStringOrNull(): ?string
         throw $this->createTypeError("is not a class-string");
     }
 
+    /**
+     * @return array<mixed>|null
+     */
     public function arrayOrNull(): ?array
     {
         if (is_array($this->value) || is_null($this->value)) {
@@ -182,6 +189,10 @@ public function instanceOfOrNull(string $className): ?object
         throw $this->createTypeError(sprintf('is not an instance of %s or null', $className));
     }
 
+    /**
+     * @param string $message
+     * @return \UnexpectedValueException
+     */
     private function createTypeError($message): \UnexpectedValueException
     {
         return new \UnexpectedValueException(get_debug_type($this->value) . ' ' . $message . ($this->additionalErrorMessage ? ' ' . $this->additionalErrorMessage : ''));
diff --git a/Neos.Utility.Files/Classes/Files.php b/Neos.Utility.Files/Classes/Files.php
index b0ff9b5b91..228e4dbe87 100644
--- a/Neos.Utility.Files/Classes/Files.php
+++ b/Neos.Utility.Files/Classes/Files.php
@@ -32,7 +32,7 @@ public static function getUnixStylePath(string $path): string
         if (strpos($path, ':') === false) {
             return str_replace(['//', '\\'], '/', $path);
         }
-        return preg_replace('/^([a-z]{2,}):\//', '$1://', str_replace(['//', '\\'], '/', $path));
+        return preg_replace('/^([a-z]{2,}):\//', '$1://', str_replace(['//', '\\'], '/', $path)) ?: '';
     }
 
     /**
@@ -53,7 +53,7 @@ public static function getNormalizedPath(string $path): string
      * Note: trailing slashes will be removed, leading slashes won't.
      * Usage: concatenatePaths(array('dir1/dir2', 'dir3', 'file'))
      *
-     * @param array $paths the file paths to be combined. Last array element may include the filename.
+     * @param array<int,string> $paths the file paths to be combined. Last array element may include the filename.
      * @return string concatenated path without trailing slash.
      * @see getUnixStylePath()
      * @api
@@ -80,10 +80,10 @@ public static function concatenatePaths(array $paths): string
      * directories.
      *
      * @param string $path Path to the directory which shall be read
-     * @param string $suffix If specified, only filenames with this extension are returned (eg. ".php" or "foo.bar")
+     * @param ?string $suffix If specified, only filenames with this extension are returned (eg. ".php" or "foo.bar")
      * @param boolean $returnRealPath If turned on, all paths are resolved by calling realpath()
      * @param boolean $returnDotFiles If turned on, also files beginning with a dot will be returned
-     * @return array Filenames including full path
+     * @return array<int,string> Filenames including full path
      * @api
      */
     public static function readDirectoryRecursively(string $path, ?string $suffix = null, bool $returnRealPath = false, bool $returnDotFiles = false): array
@@ -122,7 +122,14 @@ public static function getRecursiveDirectoryGenerator(string $path, ?string $suf
                     if (is_dir($pathAndFilename)) {
                         array_push($directories, self::getNormalizedPath($pathAndFilename));
                     } elseif ($suffix === null || strpos(strrev($filename), strrev($suffix)) === 0) {
-                        yield static::getUnixStylePath(($returnRealPath === true) ? realpath($pathAndFilename) : $pathAndFilename);
+                        if ($returnRealPath) {
+                            $nonRealPathAndFilename = $pathAndFilename;
+                            $pathAndFilename = realpath($pathAndFilename);
+                            if ($pathAndFilename === false) {
+                                throw new \RuntimeException(sprintf('Cannot get realpath for "%s". $returnRealPath cannot be used with stream wrappers.', $nonRealPathAndFilename), 1765548187);
+                            }
+                        }
+                        yield static::getUnixStylePath($pathAndFilename);
                     }
                 }
                 closedir($handle);
@@ -153,6 +160,9 @@ public static function emptyDirectoryRecursively(string $path)
         } else {
             $directoryIterator = new \RecursiveDirectoryIterator($path);
             foreach ($directoryIterator as $fileInfo) {
+                if (is_string($fileInfo)) {
+                    continue;
+                }
                 if (!$fileInfo->isDir()) {
                     if (self::unlink($fileInfo->getPathname()) !== true) {
                         throw new FilesException('Could not unlink file "' . $fileInfo->getPathname() . '".', 1169047619);
@@ -322,14 +332,12 @@ public static function copyDirectoryRecursively(string $sourceDirectory, string
      */
     public static function getFileContents(string $pathAndFilename, int $flags = 0, $context = null, int $offset = 0, int $maximumLength = -1)
     {
-        if ($flags === true) {
-            $flags = FILE_USE_INCLUDE_PATH;
-        }
+        $useIncludePath = ($flags & FILE_USE_INCLUDE_PATH) === 1;
         try {
             if ($maximumLength > -1) {
-                $content = file_get_contents($pathAndFilename, $flags, $context, $offset, $maximumLength);
+                $content = file_get_contents($pathAndFilename, $useIncludePath, $context, $offset, $maximumLength);
             } else {
-                $content = file_get_contents($pathAndFilename, $flags, $context, $offset);
+                $content = file_get_contents($pathAndFilename, $useIncludePath, $context, $offset);
             }
         } catch (ErrorException $ignoredException) {
             $content = false;
@@ -386,7 +394,7 @@ public static function is_link(string $pathAndFilename): bool
             return false;
         }
         $normalizedPathAndFilename = strtolower(rtrim(self::getUnixStylePath($pathAndFilename), '/'));
-        $normalizedTargetPathAndFilename = strtolower(self::getUnixStylePath(realpath($pathAndFilename)));
+        $normalizedTargetPathAndFilename = strtolower(self::getUnixStylePath(realpath($pathAndFilename) ?: ''));
         if ($normalizedTargetPathAndFilename === '') {
             return false;
         }
@@ -431,24 +439,26 @@ public static function unlink(string $pathAndFilename): bool
     /**
      * Supported file size units for the byte conversion functions below
      *
-     * @var array
+     * @var array<string>
      */
-    protected static $sizeUnits = ['B', 'KB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB'];
+    protected static array $sizeUnits = ['B', 'KB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB'];
 
     /**
      * Converts an integer with a byte count into human-readable form
      *
-     * @param float|integer $bytes
-     * @param integer $decimals number of decimal places in the resulting string
-     * @param string $decimalSeparator decimal separator of the resulting string
-     * @param string $thousandsSeparator thousands separator of the resulting string
+     * @param float|int $bytes
+     * @param int|null $decimals number of decimal places in the resulting string
+     * @param string|null $decimalSeparator decimal separator of the resulting string
+     * @param string|null $thousandsSeparator thousands separator of the resulting string
      * @return string the size string, e.g. "1,024 MB"
      */
     public static function bytesToSizeString($bytes, ?int $decimals = null, ?string $decimalSeparator = null, ?string $thousandsSeparator = null): string
     {
+        /** @phpstan-ignore booleanAnd.alwaysFalse (annotations may be wrong) */
         if (!is_int($bytes) && !is_float($bytes)) {
             if (is_numeric($bytes)) {
                 $bytes = (float)$bytes;
+                /** @phpstan-ignore else.unreachable (annotations may be wrong) */
             } else {
                 $bytes = 0;
             }
@@ -502,7 +512,7 @@ public static function sizeStringToBytes(string $sizeString): float
         if ($pow === false) {
             throw new FilesException(sprintf('Unknown file size unit "%s"', $matches['unit']), 1417695299);
         }
-        return $size * pow(2, (10 * $pow));
+        return $size * pow(2, (10 * (int)$pow));
     }
 
     /**
diff --git a/Neos.Utility.MediaTypes/Classes/MediaTypes.php b/Neos.Utility.MediaTypes/Classes/MediaTypes.php
index 249d21ced8..104b94a91c 100644
--- a/Neos.Utility.MediaTypes/Classes/MediaTypes.php
+++ b/Neos.Utility.MediaTypes/Classes/MediaTypes.php
@@ -33,7 +33,7 @@ abstract class MediaTypes
     /**
      * A map of file extensions to Internet Media Types
      *
-     * @var array
+     * @var array<string,string>
      */
     private static $extensionToMediaType = [
         '3dml' => 'text/vnd.in3d.3dml',
@@ -1027,7 +1027,7 @@ abstract class MediaTypes
     /**
      * A map of Internet Media Types to file extensions
      *
-     * @var array
+     * @var array<string,array<string>>
      */
     private static $mediaTypeToFileExtension = [
         'application/andrew-inset' => ['ez'],
@@ -1821,13 +1821,13 @@ public static function getMediaTypeFromFilename(string $filename): string
      * Returns a Media Type based on the file content
      *
      * @param string $fileContent The file content do determine the media type from
-     * @return string The IANA Internet Media Type
+     * @return string|null The IANA Internet Media Type
      */
-    public static function getMediaTypeFromFileContent(string $fileContent): string
+    public static function getMediaTypeFromFileContent(string $fileContent): ?string
     {
         $fileInfo = new \finfo(FILEINFO_MIME);
-        $mediaType = self::trimMediaType($fileInfo->buffer($fileContent));
-        return isset(self::$mediaTypeToFileExtension[$mediaType]) ? $mediaType : 'application/octet-stream';
+        $mediaType = self::trimMediaType($fileInfo->buffer($fileContent) ?: '');
+        return ($mediaType === null || isset(self::$mediaTypeToFileExtension[$mediaType])) ? $mediaType : 'application/octet-stream';
     }
 
     /**
@@ -1846,7 +1846,7 @@ public static function getFilenameExtensionFromMediaType(string $mediaType): str
      * Returns all possible filename extensions based on the given Media Type.
      *
      * @param string $mediaType The IANA Internet Media Type, for example "text/html"
-     * @return array The corresponding filename extensions, for example ("html", "htm")
+     * @return array<string> The corresponding filename extensions, for example ("html", "htm")
      * @api
      */
     public static function getFilenameExtensionsFromMediaType(string $mediaType): array
@@ -1867,7 +1867,7 @@ public static function getFilenameExtensionsFromMediaType(string $mediaType): ar
      * "parameters" => an array of parameter names and values, array("charset" => "UTF-8")
      *
      * @param string $rawMediaType The raw media type, for example "application/json; charset=UTF-8"
-     * @return array An associative array with parsed information
+     * @return array{type: string, subtype: string, parameters: array<string,string>} An associative array with parsed information
      */
     public static function parseMediaType(string $rawMediaType): array
     {
@@ -1921,7 +1921,7 @@ public static function mediaRangeMatches(string $mediaRange, string $mediaType):
      * and subtype in the format "type/subtype".
      *
      * @param string $rawMediaType The full media type, for example "application/json; charset=UTF-8"
-     * @return string Just the type and subtype, for example "application/json"
+     * @return string|null Just the type and subtype, for example "application/json"
      */
     public static function trimMediaType(string $rawMediaType)
     {
diff --git a/Neos.Utility.ObjectHandling/Classes/ObjectAccess.php b/Neos.Utility.ObjectHandling/Classes/ObjectAccess.php
index 89decda676..e5f0c166ed 100644
--- a/Neos.Utility.ObjectHandling/Classes/ObjectAccess.php
+++ b/Neos.Utility.ObjectHandling/Classes/ObjectAccess.php
@@ -31,15 +31,15 @@ abstract class ObjectAccess
 {
     /**
      * Internal RuntimeCache for getGettablePropertyNames()
-     * @var array
+     * @var array<string<object>,array<int,string>>
      */
-    protected static $gettablePropertyNamesCache = [];
+    protected static array $gettablePropertyNamesCache = [];
 
     /**
      * Internal RuntimeCache for getPropertyInternal()
-     * @var array
+     * @var array<string,array{accessorMethod?: string, publicProperty?: string}>
      */
-    protected static $propertyGetterCache = [];
+    protected static array $propertyGetterCache = [];
 
     const ACCESS_GET = 0;
     const ACCESS_SET = 1;
@@ -58,8 +58,8 @@ abstract class ObjectAccess
      * - if public property exists, return the value of it.
      * - else, throw exception
      *
-     * @param mixed $subject Object or array to get the property from
-     * @param string|integer $propertyName Name or index of the property to retrieve
+     * @param object|array<mixed> $subject Object or array to get the property from
+     * @param string|int $propertyName Name or index of the property to retrieve
      * @param boolean $forceDirectAccess Directly access property using reflection(!)
      * @return mixed Value of the property
      * @throws \InvalidArgumentException in case $subject was not an object or $propertyName was not a string
@@ -67,9 +67,11 @@ abstract class ObjectAccess
      */
     public static function getProperty($subject, $propertyName, bool $forceDirectAccess = false)
     {
+        /** @phpstan-ignore booleanAnd.alwaysFalse (annotations may be wrong) */
         if (!is_object($subject) && !is_array($subject)) {
             throw new \InvalidArgumentException('$subject must be an object or array, ' . gettype($subject) . ' given.', 1237301367);
         }
+        /** @phpstan-ignore booleanAnd.alwaysFalse (annotations may be wrong) */
         if (!is_string($propertyName) && !is_int($propertyName)) {
             throw new \InvalidArgumentException('Given property name/index is not of type string or integer.', 1231178303);
         }
@@ -91,14 +93,14 @@ public static function getProperty($subject, $propertyName, bool $forceDirectAcc
      * of type string you should use getProperty() instead.
      *
      * @param mixed $subject Object or array to get the property from
-     * @param string $propertyName name of the property to retrieve
+     * @param string|int $propertyName name of the property to retrieve
      * @param boolean $forceDirectAccess directly access property using reflection(!)
      * @param boolean $propertyExists (by reference) will be set to true if the specified property exists and is gettable
      * @return mixed Value of the property
      * @throws PropertyNotAccessibleException
      * @see getProperty()
      */
-    protected static function getPropertyInternal($subject, string $propertyName, bool $forceDirectAccess, bool &$propertyExists)
+    protected static function getPropertyInternal($subject, string|int $propertyName, bool $forceDirectAccess, bool &$propertyExists)
     {
         if ($subject === null) {
             return null;
@@ -111,6 +113,10 @@ protected static function getPropertyInternal($subject, string $propertyName, bo
             return null;
         }
 
+        if (is_int($propertyName)) {
+            throw new \InvalidArgumentException('Cannot use integer property names for objects', 1743799241);
+        }
+
         $propertyExists = true;
         $className = TypeHandling::getTypeForValue($subject);
 
@@ -230,7 +236,7 @@ public static function getPropertyPath($subject, string $propertyPath)
      *   on it without checking if it existed.
      * - else, return false
      *
-     * @param mixed $subject The target object or array
+     * @param array<mixed>|object $subject The target object or array
      * @param string|integer $propertyName Name or index of the property to set
      * @param mixed $propertyValue Value of the property
      * @param boolean $forceDirectAccess directly access property using reflection(!)
@@ -239,6 +245,7 @@ public static function getPropertyPath($subject, string $propertyPath)
      */
     public static function setProperty(&$subject, $propertyName, $propertyValue, bool $forceDirectAccess = false): bool
     {
+        /** @phpstan-ignore booleanAnd.alwaysFalse (annotations may be wrong) */
         if (!is_string($propertyName) && !is_int($propertyName)) {
             throw new \InvalidArgumentException('Given property name/index is not of type string or integer.', 1231178878);
         }
@@ -261,8 +268,8 @@ public static function setProperty(&$subject, $propertyName, $propertyValue, boo
                 $propertyReflection = new \ReflectionProperty($className, $propertyName);
                 $propertyReflection->setAccessible(true);
                 $propertyReflection->setValue($subject, $propertyValue);
-            } elseif ($subject instanceof ProxyInterface && property_exists(get_parent_class($className), $propertyName)) {
-                $propertyReflection = new \ReflectionProperty(get_parent_class($className), $propertyName);
+            } elseif ($subject instanceof ProxyInterface && property_exists(get_parent_class($className) ?: $className, $propertyName)) {
+                $propertyReflection = new \ReflectionProperty(get_parent_class($className) ?: $className, $propertyName);
                 $propertyReflection->setAccessible(true);
                 $propertyReflection->setValue($subject, $propertyValue);
             } else {
@@ -290,7 +297,7 @@ public static function setProperty(&$subject, $propertyName, $propertyValue, boo
      * - public properties which can be directly get.
      *
      * @param object $object Object to receive property names for
-     * @return array Array of all gettable property names
+     * @return array<int,string> Array of all gettable property names
      * @throws \InvalidArgumentException
      */
     public static function getGettablePropertyNames($object): array
@@ -336,7 +343,7 @@ public static function getGettablePropertyNames($object): array
      * - public properties which can be directly set.
      *
      * @param object $object Object to receive property names for
-     * @return array Array of all settable property names
+     * @return array<int,string> Array of all settable property names
      * @throws \InvalidArgumentException
      */
     public static function getSettablePropertyNames($object): array
@@ -376,6 +383,7 @@ public static function isPropertySettable($object, string $propertyName): bool
             throw new \InvalidArgumentException('$object must be an object, ' . gettype($object) . ' given.', 1259828920);
         }
 
+        /** @var string $className safe for objects */
         $className = TypeHandling::getTypeForValue($object);
         if (($object instanceof \stdClass && array_key_exists($propertyName, get_object_vars($object))) || array_key_exists($propertyName, get_class_vars($className))) {
             return true;
@@ -412,7 +420,7 @@ public static function isPropertyGettable($object, string $propertyName): bool
      * $object that are accessible through this class.
      *
      * @param object $object Object to get all properties from.
-     * @return array Associative array of all properties.
+     * @return array<string,mixed> Associative array of all properties.
      * @throws \InvalidArgumentException
      * @todo What to do with ArrayAccess
      */
diff --git a/Neos.Utility.ObjectHandling/Classes/TypeHandling.php b/Neos.Utility.ObjectHandling/Classes/TypeHandling.php
index c078b86b71..a134b02504 100644
--- a/Neos.Utility.ObjectHandling/Classes/TypeHandling.php
+++ b/Neos.Utility.ObjectHandling/Classes/TypeHandling.php
@@ -31,16 +31,16 @@ abstract class TypeHandling
     const LITERAL_TYPE_PATTERN = '/^(?:integer|int|float|double|boolean|bool|string)$/';
 
     /**
-     * @var array
+     * @var array<int,string|class-string<\Traversable<mixed>>>
      */
-    protected static $collectionTypes = ['array', \Traversable::class];
+    protected static array $collectionTypes = ['array', \Traversable::class];
 
     /**
      * Returns an array with type information, including element type for
      * collection types (array, SplObjectStorage, ...)
      *
      * @param string $type Type of the property (see PARSE_TYPE_PATTERN)
-     * @return array An array with information about the type
+     * @return array{type: string, elementType: ?string, nullable: bool} An array with information about the type
      * @throws InvalidTypeException
      */
     public static function parseType(string $type): array
@@ -52,7 +52,7 @@ public static function parseType(string $type): array
 
         $typeWithoutNull = self::stripNullableType($type);
         $isNullable = $typeWithoutNull !== $type || $type === 'null';
-        $type = self::normalizeType($matches['type']);
+        $type = self::normalizeType($matches['type'] ?? '');
         $elementType = isset($matches['elementType']) ? self::normalizeType($matches['elementType']) : null;
 
         if ($elementType !== null && !self::isCollectionType($type)) {
@@ -116,7 +116,7 @@ public static function isSimpleType(string $type): bool
     /**
      * Returns true if the $type is a collection type.
      *
-     * @param string $type
+     * @param string|class-string<object> $type
      * @return boolean
      */
     public static function isCollectionType(string $type): bool
@@ -127,8 +127,11 @@ public static function isCollectionType(string $type): bool
 
         if (class_exists($type) === true || interface_exists($type) === true) {
             foreach (self::$collectionTypes as $collectionType) {
-                if (is_subclass_of($type, $collectionType) === true) {
-                    return true;
+                if (class_exists($collectionType) || interface_exists($collectionType)) {
+                    /** @var class-string<\Traversable<mixed>> $collectionType */
+                    if (is_subclass_of($type, $collectionType) === true) {
+                        return true;
+                    }
                 }
             }
         }
@@ -185,7 +188,7 @@ public static function stripNullableType($type)
         if (stripos($type, 'null') === false) {
             return $type;
         }
-        return preg_replace('/(\\|null|null\\|)/i', '', $type);
+        return preg_replace('/(\\|null|null\\|)/i', '', $type) ?: '';
     }
 
     /**
@@ -199,12 +202,12 @@ public static function getTypeForValue($value): string
         if (is_object($value)) {
             if ($value instanceof Proxy) {
                 $type = get_parent_class($value);
-            } else {
-                $type = get_class($value);
+                if ($type !== false) {
+                    return $type;
+                }
             }
-        } else {
-            $type = gettype($value);
+            return get_class($value);
         }
-        return $type;
+        return gettype($value);
     }
 }
diff --git a/Neos.Utility.Pdo/Classes/PdoHelper.php b/Neos.Utility.Pdo/Classes/PdoHelper.php
index 873ef34621..40ac1dac76 100644
--- a/Neos.Utility.Pdo/Classes/PdoHelper.php
+++ b/Neos.Utility.Pdo/Classes/PdoHelper.php
@@ -33,7 +33,7 @@ abstract class PdoHelper
      * @param \PDO $databaseHandle
      * @param string $pdoDriver
      * @param string $pathAndFilename
-     * @param array $replacePairs every key in this array will be replaced with the corresponding value in the loaded SQL (example: ['###CACHE_TABLE_NAME###' => 'caches', '###TAGS_TABLE_NAME###' => 'tags'])
+     * @param array<string,string> $replacePairs every key in this array will be replaced with the corresponding value in the loaded SQL (example: ['###CACHE_TABLE_NAME###' => 'caches', '###TAGS_TABLE_NAME###' => 'tags'])
      * @return void
      */
     public static function importSql(\PDO $databaseHandle, string $pdoDriver, string $pathAndFilename, array $replacePairs = [])
@@ -46,13 +46,13 @@ public static function importSql(\PDO $databaseHandle, string $pdoDriver, string
         } else {
             $sql = file($pathAndFilename, FILE_IGNORE_NEW_LINES & FILE_SKIP_EMPTY_LINES);
             // Remove MySQL style key length delimiters (yuck!) if we are not setting up a MySQL db
-            if ($pdoDriver !== 'mysql') {
+            if ($sql !== false && $pdoDriver !== 'mysql') {
                 $sql = preg_replace('/"\([0-9]+\)/', '"', $sql);
             }
         }
 
         $statement = '';
-        foreach ($sql as $line) {
+        foreach ($sql ?: [] as $line) {
             $statement .= ' ' . trim(strtr($line, $replacePairs));
             if (substr($statement, -1) === ';') {
                 $databaseHandle->exec($statement);
diff --git a/Neos.Utility.Schema/Classes/SchemaGenerator.php b/Neos.Utility.Schema/Classes/SchemaGenerator.php
index 07a977c120..5ac82327d2 100644
--- a/Neos.Utility.Schema/Classes/SchemaGenerator.php
+++ b/Neos.Utility.Schema/Classes/SchemaGenerator.php
@@ -26,7 +26,7 @@ class SchemaGenerator
      * Generate a schema for the given value
      *
      * @param mixed $value value to create a schema for
-     * @return array schema as array structure
+     * @return array<string,mixed> schema as array structure
      */
     public function generate($value): array
     {
@@ -62,8 +62,8 @@ public function generate($value): array
     /**
      * Create a schema for a dictionary
      *
-     * @param array $dictionaryValue
-     * @return array
+     * @param array<mixed> $dictionaryValue
+     * @return array{type: string, properties: array<mixed>}
      */
     protected function generateDictionarySchema(array $dictionaryValue): array
     {
@@ -78,8 +78,8 @@ protected function generateDictionarySchema(array $dictionaryValue): array
     /**
      * Create a schema for an array structure
      *
-     * @param array $arrayValue
-     * @return array schema
+     * @param array<mixed> $arrayValue
+     * @return array<string,mixed> schema
      */
     protected function generateArraySchema(array $arrayValue): array
     {
@@ -96,7 +96,7 @@ protected function generateArraySchema(array $arrayValue): array
      * Create a schema for a given string
      *
      * @param string $stringValue
-     * @return array
+     * @return array<string,mixed>
      */
     protected function generateStringSchema(string $stringValue): array
     {
@@ -122,7 +122,7 @@ protected function generateStringSchema(string $stringValue): array
      * Compact an array of items to avoid adding the same value more than once.
      * If the result contains only one item, that item is returned directly.
      *
-     * @param array $values array of values
+     * @param array<mixed> $values array of values
      * @return mixed
      */
     protected function filterDuplicatesFromArray(array $values)
diff --git a/Neos.Utility.Schema/Classes/SchemaValidator.php b/Neos.Utility.Schema/Classes/SchemaValidator.php
index 64fec01df2..82427d9827 100644
--- a/Neos.Utility.Schema/Classes/SchemaValidator.php
+++ b/Neos.Utility.Schema/Classes/SchemaValidator.php
@@ -69,7 +69,7 @@ class SchemaValidator
      *
      * @param mixed $value value to validate
      * @param mixed $schema type as string, schema or array of schemas
-     * @param array $types the additional type schemas
+     * @param array<mixed> $types the additional type schemas
      * @return ErrorResult
      */
     public function validate($value, $schema, array $types = []): ErrorResult
@@ -147,8 +147,8 @@ public function validate($value, $schema, array $types = []): ErrorResult
      * Validate a value for a given type
      *
      * @param mixed $value
-     * @param array $schema
-     * @param array $types
+     * @param array<string,mixed> $schema
+     * @param array<mixed> $types
      * @return ErrorResult
      */
     protected function validateType($value, array $schema, array $types = []): ErrorResult
@@ -209,8 +209,8 @@ protected function validateType($value, array $schema, array $types = []): Error
      * Validate a value with a given list of allowed types
      *
      * @param mixed $value
-     * @param array $schema
-     * @param array $types
+     * @param array<string,mixed> $schema
+     * @param array<mixed> $types
      * @return ErrorResult
      */
     protected function validateTypeArray($value, array $schema, array $types = []): ErrorResult
@@ -254,7 +254,7 @@ protected function validateTypeArray($value, array $schema, array $types = []):
      * - divisibleBy : value is divisibleBy the given number
      *
      * @param mixed $value
-     * @param array $schema
+     * @param array<string,mixed> $schema
      * @return ErrorResult
      */
     protected function validateNumberType($value, array $schema): ErrorResult
@@ -305,7 +305,7 @@ protected function validateNumberType($value, array $schema): ErrorResult
      *
      * @see SchemaValidator::validateNumberType
      * @param mixed $value
-     * @param array $schema
+     * @param array<mixed> $schema
      * @return ErrorResult
      */
     protected function validateIntegerType($value, array $schema): ErrorResult
@@ -323,7 +323,7 @@ protected function validateIntegerType($value, array $schema): ErrorResult
      * Validate a boolean value with the given schema
      *
      * @param mixed $value
-     * @param array $schema
+     * @param array<mixed> $schema
      * @return ErrorResult
      */
     protected function validateBooleanType($value, array $schema): ErrorResult
@@ -346,8 +346,8 @@ protected function validateBooleanType($value, array $schema): ErrorResult
      * - uniqueItems : allow only unique values
      *
      * @param mixed $value
-     * @param array $schema
-     * @param array $types
+     * @param array<string,mixed> $schema
+     * @param array<mixed> $types
      * @return ErrorResult
      */
     protected function validateArrayType($value, array $schema, array $types = []): ErrorResult
@@ -404,8 +404,8 @@ protected function validateArrayType($value, array $schema, array $types = []):
      * - additionalProperties : if false is given all additionalProperties are forbidden, if a schema is given all additional properties have to match the schema
      *
      * @param mixed $value
-     * @param array $schema
-     * @param array $types
+     * @param array<int|string,mixed> $schema
+     * @param array<int|string,mixed> $types
      * @return ErrorResult
      */
     protected function validateDictionaryType($value, array $schema, array $types = []): ErrorResult
@@ -496,8 +496,8 @@ protected function validateDictionaryType($value, array $schema, array $types =
      *   [date-time|date|time|uri|email|ipv4|ipv6|ip-address|host-name|class-name|interface-name]
      *
      * @param mixed $value
-     * @param array $schema
-     * @param array $types
+     * @param array<string,mixed> $schema
+     * @param array<mixed> $types
      * @return ErrorResult
      */
     protected function validateStringType($value, array $schema, array $types = []): ErrorResult
@@ -530,6 +530,7 @@ protected function validateStringType($value, array $schema, array $types = []):
             switch ($schema['format']) {
                 case 'date-time':
                     // YYYY-MM-DDThh:mm:ssZ ISO8601
+                    /** @phpstan-ignore staticMethod.resultUnused (we only care about the error) */
                     \DateTime::createFromFormat(\DateTime::ISO8601, $value);
                     $parseErrors = \DateTime::getLastErrors();
                     if ($parseErrors && $parseErrors['error_count'] > 0) {
@@ -538,6 +539,7 @@ protected function validateStringType($value, array $schema, array $types = []):
                     break;
                 case 'date':
                     // YYYY-MM-DD
+                    /** @phpstan-ignore staticMethod.resultUnused (we only care about the error) */
                     \DateTime::createFromFormat('Y-m-d', $value);
                     $parseErrors = \DateTime::getLastErrors();
                     if ($parseErrors && $parseErrors['error_count'] > 0) {
@@ -546,6 +548,7 @@ protected function validateStringType($value, array $schema, array $types = []):
                     break;
                 case 'time':
                     // hh:mm:ss
+                    /** @phpstan-ignore staticMethod.resultUnused (we only care about the error) */
                     \DateTime::createFromFormat('H:i:s', $value);
                     $parseErrors = \DateTime::getLastErrors();
                     if ($parseErrors && $parseErrors['error_count'] > 0) {
@@ -604,7 +607,7 @@ protected function validateStringType($value, array $schema, array $types = []):
      * Validate a null value with the given schema
      *
      * @param mixed $value
-     * @param array $schema
+     * @param array<mixed> $schema
      * @return ErrorResult
      */
     protected function validateNullType($value, array $schema): ErrorResult
@@ -620,7 +623,7 @@ protected function validateNullType($value, array $schema): ErrorResult
      * Validate any value with the given schema. Return always a valid Result.
      *
      * @param mixed $value
-     * @param array $schema
+     * @param array<int|string,mixed> $schema
      * @return ErrorResult
      */
     protected function validateAnyType($value, array $schema): ErrorResult
@@ -665,7 +668,7 @@ protected function createError(string $expectation, $value = null): Error
      * Determine whether the given php array is a schema or not
      *
      * @todo there should be a more sophisticated way to detect schemas
-     * @param array $phpArray
+     * @param array<int|string, mixed> $phpArray
      * @return boolean
      */
     protected function isSchema(array $phpArray): bool
@@ -677,7 +680,7 @@ protected function isSchema(array $phpArray): bool
     /**
      * Determine whether the given php array is a plain numerically indexed array
      *
-     * @param array $phpArray
+     * @param array<int|string,mixed> $phpArray
      * @return boolean
      */
     protected function isNumericallyIndexedArray(array $phpArray): bool
@@ -693,7 +696,7 @@ protected function isNumericallyIndexedArray(array $phpArray): bool
     /**
      * Determine whether the given php array is a Dictionary (has no numeric identifiers)
      *
-     * @param array $phpArray
+     * @param array<int|string, mixed> $phpArray
      * @return boolean
      */
     protected function isDictionary(array $phpArray): bool
diff --git a/Neos.Utility.Unicode/Classes/Functions.php b/Neos.Utility.Unicode/Classes/Functions.php
index a13429ebb5..12cfd22a11 100644
--- a/Neos.Utility.Unicode/Classes/Functions.php
+++ b/Neos.Utility.Unicode/Classes/Functions.php
@@ -31,7 +31,7 @@ public static function strtotitle(string $string): string
     {
         $result = '';
         $splitIntoLowerCaseWords = preg_split("/([\n\r\t ])/", self::strtolower($string), -1, PREG_SPLIT_DELIM_CAPTURE);
-        foreach ($splitIntoLowerCaseWords as $delimiterOrValue) {
+        foreach ($splitIntoLowerCaseWords ?: [] as $delimiterOrValue) {
             $result .= self::strtoupper(self::substr($delimiterOrValue, 0, 1)) . self::substr($delimiterOrValue, 1);
         }
         return $result;
@@ -133,7 +133,7 @@ public static function lcfirst(string $string): string
      * @param string $haystack UTF-8 string to search in
      * @param string $needle UTF-8 string to search for
      * @param integer $offset Positition to start the search
-     * @return integer The character position
+     * @return integer|false The character position
      * @api
      */
     public static function strpos(string $haystack, string $needle, int $offset = 0)
@@ -154,16 +154,19 @@ public static function strpos(string $haystack, string $needle, int $offset = 0)
      * @see http://www.php.net/manual/en/function.pathinfo.php
      *
      * @param string $path
-     * @param integer $options Optional, one of PATHINFO_DIRNAME, PATHINFO_BASENAME, PATHINFO_EXTENSION or PATHINFO_FILENAME.
-     * @return string|array
+     * @param integer|null $options Optional, one of PATHINFO_DIRNAME, PATHINFO_BASENAME, PATHINFO_EXTENSION or PATHINFO_FILENAME.
+     * @return string|array{dirname: string, basename: string, extension: string, filename: string}
      * @api
      */
-    public static function pathinfo(string $path, ?int $options = null)
+    public static function pathinfo(string $path, ?int $options = null): string|array
     {
+        /** @var string $currentLocale we assume the current locale to be properly set */
+        /** @phpstan-ignore argument.type (int is allowed for locales) */
         $currentLocale = setlocale(LC_CTYPE, 0);
         // Before we have a setting for setlocale, his should suffice for pathinfo
         // to work correctly on Unicode strings
         setlocale(LC_CTYPE, 'en_US.UTF-8');
+        /** @var string|array{dirname: string, basename: string, extension: string, filename: string} $pathinfo */
         $pathinfo = $options == null ? pathinfo($path) : pathinfo($path, $options);
         setlocale(LC_CTYPE, $currentLocale);
         return $pathinfo;
@@ -188,8 +191,11 @@ public static function parse_url(string $url, int $component = -1)
         $encodedUrl = preg_replace_callback('%[^:@/?#&=\.]+%usD', function ($matches) {
             return urlencode($matches[0]);
         }, $url);
-        $components = parse_url($encodedUrl);
+        if ($encodedUrl === null) {
+            return false;
+        }
 
+        $components = parse_url($encodedUrl);
         if ($components === false) {
             return false;
         }
diff --git a/Neos.Utility.Unicode/Classes/TextIterator.php b/Neos.Utility.Unicode/Classes/TextIterator.php
index 862a05c204..2af09dd48d 100644
--- a/Neos.Utility.Unicode/Classes/TextIterator.php
+++ b/Neos.Utility.Unicode/Classes/TextIterator.php
@@ -19,6 +19,7 @@
 /**
  * A UTF8-aware TextIterator
  *
+ * @implements \Iterator<int,string>
  */
 class TextIterator implements \Iterator
 {
@@ -68,12 +69,12 @@ class TextIterator implements \Iterator
     protected $currentPosition;
 
     /**
-     * @var \ArrayObject
+     * @var \ArrayObject<int,TextIteratorElement>
      */
     protected $iteratorCache;
 
     /**
-     * @var \ArrayIterator
+     * @var \ArrayIterator<int,TextIteratorElement>
      */
     protected $iteratorCacheIterator;
 
@@ -109,11 +110,11 @@ public function __construct(string $subject, int $iteratorType = self::CHARACTER
     /**
      * Returns the current element
      *
-     * @return string The value of the current element
+     * @return string|null The value of the current element
      */
-    public function current(): string
+    public function current(): ?string
     {
-        return $this->getCurrentElement()->getValue();
+        return $this->getCurrentElement()?->getValue();
     }
 
     /**
@@ -123,7 +124,7 @@ public function current(): string
      */
     public function next(): void
     {
-        $this->previousElement = $this->getCurrentElement();
+        $this->previousElement = $this->getCurrentElement() ?: $this->previousElement;
         $this->iteratorCacheIterator->next();
     }
 
@@ -164,11 +165,11 @@ public function rewind(): void
     /**
      * Returns the offset in the original given string of the current element
      *
-     * @return integer The offset of the current element
+     * @return int|null The offset of the current element, if any
      */
-    public function offset(): int
+    public function offset(): ?int
     {
-        return $this->getCurrentElement()->getOffset();
+        return $this->getCurrentElement()?->getOffset();
     }
 
     /**
@@ -194,7 +195,8 @@ public function last(): string
             $previousElement = $this->getCurrentElement();
             $this->next();
         }
-        return $previousElement->getValue();
+        // can never be null because the iterator cannot be empty
+        return $previousElement?->getValue() ?: '';
     }
 
     /**
@@ -202,15 +204,15 @@ public function last(): string
      * given by its offset
      *
      * @param integer $offset The offset of the character
-     * @return int The offset of the element following this character
+     * @return int|null The offset of the element following this character or null if the offset is out of bounds
      */
-    public function following(int $offset): int
+    public function following(int $offset): ?int
     {
         $this->rewind();
         while ($this->valid()) {
             $this->next();
             $nextElement = $this->getCurrentElement();
-            if ($nextElement->getOffset() >= $offset) {
+            if ($nextElement && $nextElement->getOffset() >= $offset) {
                 return $nextElement->getOffset();
             }
         }
@@ -231,7 +233,7 @@ public function preceding(int $offset): int
             $previousElement = $this->getCurrentElement();
             $this->next();
             $currentElement = $this->getCurrentElement();
-            if (($currentElement->getOffset() + $currentElement->getLength()) >= $offset) {
+            if ($previousElement && $currentElement && ($currentElement->getOffset() + $currentElement->getLength()) >= $offset) {
                 return $previousElement->getOffset() + $previousElement->getLength();
             }
         }
@@ -254,20 +256,21 @@ public function preceding(int $offset): int
      */
     public function isBoundary(): bool
     {
-        return $this->getCurrentElement()->isBoundary();
+        return $this->getCurrentElement()?->isBoundary() ?: false;
     }
 
     /**
      * Returns all elements of the iterator in an array
      *
-     * @return array All elements of the iterator
+     * @return array<int,string> All elements of the iterator
      */
     public function getAll(): array
     {
         $this->rewind();
         $allValues = [];
         while ($this->valid()) {
-            $allValues[] = $this->getCurrentElement()->getValue();
+            // will never be null while valid
+            $allValues[] = $this->getCurrentElement()?->getValue() ?: '';
             $this->next();
         }
         return $allValues;
@@ -276,7 +279,7 @@ public function getAll(): array
     /**
      * @throws UnsupportedFeatureException
      */
-    public function getRuleStatus()
+    public function getRuleStatus(): never
     {
         throw new UnsupportedFeatureException('getRuleStatus() is not supported.', 1210849057);
     }
@@ -284,7 +287,7 @@ public function getRuleStatus()
     /**
      * @throws UnsupportedFeatureException
      */
-    public function getRuleStatusArray()
+    public function getRuleStatusArray(): never
     {
         throw new UnsupportedFeatureException('getRuleStatusArray() is not supported.', 1210849076);
     }
@@ -292,7 +295,7 @@ public function getRuleStatusArray()
     /**
      * @throws UnsupportedFeatureException
      */
-    public function getAvailableLocales()
+    public function getAvailableLocales(): never
     {
         throw new UnsupportedFeatureException('getAvailableLocales() is not supported.', 1210849105);
     }
@@ -305,7 +308,8 @@ public function getAvailableLocales()
     public function first(): string
     {
         $this->rewind();
-        return $this->getCurrentElement()->getValue();
+        // can never be empty, will at least contain empty string
+        return $this->getCurrentElement()?->getValue() ?: '';
     }
 
     /**
@@ -346,7 +350,7 @@ private function generateIteratorElements()
     private function parseSubjectByCharacter(): void
     {
         $i = 0;
-        foreach (preg_split('//u', $this->subject) as $currentCharacter) {
+        foreach (preg_split('//u', $this->subject) ?: [] as $currentCharacter) {
             if ($currentCharacter === '') {
                 continue;
             }
@@ -373,7 +377,7 @@ private function parseSubjectByWord()
                 $this->iteratorCache->append(new TextIteratorElement(' ', $i, 1, true));
 
                 $j = 0;
-                $splittedWord = preg_split('/' . self::REGEXP_SENTENCE_DELIMITERS . '/', $currentWord);
+                $splittedWord = preg_split('/' . self::REGEXP_SENTENCE_DELIMITERS . '/', $currentWord) ?: [];
                 foreach ($splittedWord as $currentPart) {
                     if ($currentPart !== '') {
                         $this->iteratorCache->append(new TextIteratorElement($currentPart, $i, Unicode\Functions::strlen($currentPart), false));
@@ -442,7 +446,7 @@ private function parseSubjectBySentence()
         $count = 0;
         $delimitersMatches = [];
         preg_match_all('/' . self::REGEXP_SENTENCE_DELIMITERS . '/', $this->subject, $delimitersMatches);
-        $splittedSentence = preg_split('/' . self::REGEXP_SENTENCE_DELIMITERS . '/', $this->subject);
+        $splittedSentence = preg_split('/' . self::REGEXP_SENTENCE_DELIMITERS . '/', $this->subject) ?: [];
 
         if (count($splittedSentence) == 1) {
             $this->iteratorCache->append(new TextIteratorElement($splittedSentence[0], 0, Unicode\Functions::strlen($splittedSentence[0]), false));
@@ -480,6 +484,7 @@ private function parseSubjectBySentence()
      * Helper function to get the current element from the cache.
      *
      * @return TextIteratorElement|null The current element of the cache
+     * @phpstan-ignore return.unusedType (can be null if next() leaves the valid range of the iterator)
      */
     private function getCurrentElement()
     {
diff --git a/composer.json b/composer.json
index 2da6973341..ddc2981598 100644
--- a/composer.json
+++ b/composer.json
@@ -10,9 +10,11 @@
             "../../flow doctrine:migrate --quiet",
             "../../bin/behat -f progress -c Neos.Flow/Tests/Behavior/behat.yml"
         ],
-        "lint:phpstan": "../../bin/phpstan analyse",
+        "lint:phpstan-legacy": "../../bin/phpstan analyse -c phpstan-legacy.neon.dist",
+        "lint:phpstan": "../../bin/phpstan analyse -c phpstan.neon.dist",
         "lint": [
-            "@lint:phpstan"
+            "@lint:phpstan",
+            "@lint:phpstan-legacy"
         ]
     },
     "require": {
diff --git a/phpstan-legacy.neon.dist b/phpstan-legacy.neon.dist
new file mode 100644
index 0000000000..168406b3ec
--- /dev/null
+++ b/phpstan-legacy.neon.dist
@@ -0,0 +1,20 @@
+# packages we yet only lint with lvl 3 - thus _legacy_ configuration :)
+parameters:
+    level: 3
+    paths:
+        - Neos.Cache/Classes
+        - Neos.Eel/Classes
+        - Neos.Error.Messages/Classes
+        - Neos.Flow/Classes
+    bootstrapFiles:
+         - bootstrap-phpstan.php
+    excludePaths:
+        analyse:
+            - Neos.Flow/.phpstorm.meta.php
+            # The parsers are autogenerated / extending autogenerated code and not analysable
+            - Neos.Eel/Classes/FlowQuery/FizzleParser.php
+            - Neos.Eel/Classes/AbstractParser.php
+            - Neos.Eel/Classes/EelParser.php
+            - Neos.Eel/Classes/InterpretedEelParser.php
+            - Neos.Eel/Classes/CompilingEelParser.php
+            - Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/EntityPrivilegeExpressionEvaluator.php
diff --git a/phpstan.neon.dist b/phpstan.neon.dist
index 9b730bf93b..e568d138a5 100644
--- a/phpstan.neon.dist
+++ b/phpstan.neon.dist
@@ -1,10 +1,6 @@
 parameters:
-    level: 3
+    level: 8
     paths:
-        - Neos.Cache/Classes
-        - Neos.Eel/Classes
-        - Neos.Error.Messages/Classes
-        - Neos.Flow/Classes
         - Neos.Flow.Log/Classes
         - Neos.FluidAdaptor/Classes
         - Neos.Http.Factories/Classes
@@ -29,3 +25,6 @@ parameters:
             - Neos.Eel/Classes/InterpretedEelParser.php
             - Neos.Eel/Classes/CompilingEelParser.php
             - Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/EntityPrivilegeExpressionEvaluator.php
+    scanDirectories:
+        - Neos.Flow/Tests
+        - Neos.Flow/Classes/Error