[Forwardport] Added checks to see if the payment is available

app/code/Magento/Payment/Observer/SalesOrderBeforeSaveObserver.php

@@ -15,12 +15,19 @@ class SalesOrderBeforeSaveObserver implements ObserverInterface
      *
      * @param \Magento\Framework\Event\Observer $observer
      * @return $this
+     * @throws \Magento\Framework\Exception\LocalizedException in case order has no payment specified.
      */
     public function execute(\Magento\Framework\Event\Observer $observer)
     {
         /** @var \Magento\Sales\Model\Order $order */
         $order = $observer->getEvent()->getOrder();
 
+        if (!$order->getPayment()) {
+            throw new \Magento\Framework\Exception\LocalizedException(
+                __('Please provide payment for the order.')
+            );
+        }
+
         if ($order->getPayment()->getMethodInstance()->getCode() != 'free') {
             return $this;
         }

app/code/Magento/Payment/Test/Unit/Observer/SalesOrderBeforeSaveObserverTest.php

@@ -61,7 +61,7 @@ public function testSalesOrderBeforeSaveCantUnhold()
         $paymentMock = $this->getMockBuilder(
             \Magento\Sales\Model\Order\Payment::class
         )->disableOriginalConstructor()->setMethods([])->getMock();
-        $order->expects($this->once())->method('getPayment')->will($this->returnValue($paymentMock));
+        $order->method('getPayment')->will($this->returnValue($paymentMock));
         $methodInstance = $this->getMockBuilder(
             \Magento\Payment\Model\MethodInterface::class
         )->getMockForAbstractClass();
@@ -86,7 +86,7 @@ public function testSalesOrderBeforeSaveIsCanceled()
         $paymentMock = $this->getMockBuilder(
             \Magento\Sales\Model\Order\Payment::class
         )->disableOriginalConstructor()->setMethods([])->getMock();
-        $order->expects($this->once())->method('getPayment')->will($this->returnValue($paymentMock));
+        $order->method('getPayment')->will($this->returnValue($paymentMock));
         $methodInstance = $this->getMockBuilder(
             \Magento\Payment\Model\MethodInterface::class
         )->getMockForAbstractClass();
@@ -114,7 +114,7 @@ public function testSalesOrderBeforeSaveIsClosed()
         $paymentMock = $this->getMockBuilder(
             \Magento\Sales\Model\Order\Payment::class
         )->disableOriginalConstructor()->setMethods([])->getMock();
-        $order->expects($this->once())->method('getPayment')->will($this->returnValue($paymentMock));
+        $order->method('getPayment')->will($this->returnValue($paymentMock));
         $methodInstance = $this->getMockBuilder(
             \Magento\Payment\Model\MethodInterface::class
         )->getMockForAbstractClass();
@@ -156,6 +156,29 @@ public function testSalesOrderBeforeSaveSetForced()
         $this->salesOrderBeforeSaveObserver->execute($this->observerMock);
     }
 
+    /**
+     * The method should check that the payment is available, as this is not always the case.
+     *
+     * @expectedException \Magento\Framework\Exception\LocalizedException
+     * @exceptedExceptionMessage Please provide payment for the order.
+     */
+    public function testDoesNothingWhenNoPaymentIsAvailable()
+    {
+        $this->_prepareEventMockWithMethods(['getOrder']);
+
+        $order = $this->getMockBuilder(\Magento\Sales\Model\Order::class)->disableOriginalConstructor()->setMethods(
+            array_merge(['__wakeup', 'getPayment'])
+        )->getMock();
+
+        $this->eventMock->expects($this->once())->method('getOrder')->will(
+            $this->returnValue($order)
+        );
+
+        $order->expects($this->exactly(1))->method('getPayment')->willReturn(null);
+
+        $this->salesOrderBeforeSaveObserver->execute($this->observerMock);
+    }
+
     /**
      * Prepares EventMock with set of methods
      *
@@ -184,7 +207,7 @@ private function _getPreparedOrderMethod($methodCode, $orderMethods = [])
         $paymentMock = $this->getMockBuilder(
             \Magento\Sales\Model\Order\Payment::class
         )->disableOriginalConstructor()->setMethods([])->getMock();
-        $order->expects($this->once())->method('getPayment')->will($this->returnValue($paymentMock));
+        $order->method('getPayment')->will($this->returnValue($paymentMock));
         $methodInstance = $this->getMockBuilder(
             \Magento\Payment\Model\MethodInterface::class
         )->getMockForAbstractClass();

app/code/Magento/Paypal/Plugin/OrderCanInvoice.php

@@ -40,6 +40,10 @@ public function __construct(Express $express)
      */
     public function afterCanInvoice(Order $order, bool $result): bool
     {
+        if (!$order->getPayment()) {
+            return false;
+        }
+
         if ($this->express->isOrderAuthorizationAllowed($order->getPayment())) {
             return false;
         }