Don't instantiate plugins until it's time to install them

Fixes #15506

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## Unreleased
 
 - Fixed an error that could occur if a new element was saved recursively. ([#15517](https://github.com/craftcms/cms/issues/15517))
+- Fixed a bug where plugins were being instantiated at the beginning of Craft installation requests, rather than after Craft was installed. ([#15506](https://github.com/craftcms/cms/issues/15506))
 
 ## 4.11.1 - 2024-08-07
 

src/migrations/Install.php

@@ -29,6 +29,7 @@
 use craft\models\Site;
 use craft\services\ProjectConfig;
 use craft\web\Response;
+use ReflectionClass;
 
 /**
  * Installation Migration
@@ -1194,21 +1195,18 @@ private function _validateProjectConfig(string &$error = null): bool
         // and that they have the same schema as project.yaml
         foreach ($pluginConfigs as $handle => $pluginConfig) {
             try {
-                $plugin = $pluginsService->createPlugin($handle);
+                $pluginInfo = $pluginsService->getPluginInfo($handle);
             } catch (InvalidPluginException) {
                 $error = "The “{$handle}” plugin is not Composer-installed, but project.yaml expects it to be.";
                 return false;
             }
 
-            if (!$plugin) {
-                $error = "“{$handle}” is not a valid plugin.";
-                return false;
-            }
-
+            $pluginRef = new ReflectionClass($pluginInfo['class']);
+            $schemaVersion = $pluginRef->getProperty('schemaVersion')->getDefaultValue();
             $expectedSchemaVersion = $pluginConfig['schemaVersion'] ?? null;
 
-            if ($plugin->schemaVersion && $expectedSchemaVersion && $plugin->schemaVersion != $expectedSchemaVersion) {
-                $error = "$plugin->name is installed with schema version $plugin->schemaVersion, but project.yaml expects $expectedSchemaVersion.";
+            if ($schemaVersion && $expectedSchemaVersion && $schemaVersion != $expectedSchemaVersion) {
+                $error = "{$pluginInfo['name']} is installed with schema version $schemaVersion, but project.yaml expects $expectedSchemaVersion.";
                 return false;
             }
         }