symfony
diff --git a/‎src/Symfony/Component/Messenger/DependencyInjection/MessengerPass.php
Lines changed: 14 additions & 1 deletion b/‎src/Symfony/Component/Messenger/DependencyInjection/MessengerPass.php
Lines changed: 14 additions & 1 deletion
diff --git a/‎src/Symfony/Component/Messenger/Tests/DependencyInjection/MessengerPassTest.php
Lines changed: 29 additions & 0 deletions b/‎src/Symfony/Component/Messenger/Tests/DependencyInjection/MessengerPassTest.php
Lines changed: 29 additions & 0 deletions
@@ -79,7 +79,7 @@ private function registerHandlers(ContainerBuilder $container, array $busIds)
                     throw new RuntimeException(sprintf('Invalid handler service "%s": bus "%s" specified on the tag "%s" does not exist (known ones are: %s).', $serviceId, $tag['bus'], $this->handlerTag, implode(', ', $busIds)));
                 }
 
-                $className = $container->getDefinition($serviceId)->getClass();
+                $className = $this->getDefinitionClass($serviceId, $container);
                 $r = $container->getReflectionClass($className);
 
                 if (null === $r) {
@@ -321,4 +321,17 @@ private function registerBusMiddleware(ContainerBuilder $container, string $busI
 
         $container->getDefinition($busId)->replaceArgument(0, new IteratorArgument($middlewareReferences));
     }
+
+    private function getDefinitionClass(string $serviceId, ContainerBuilder $container)
+    {
+        $serviceIdDefinition = $container->getDefinition($serviceId);
+        while ($serviceIdDefinition instanceof ChildDefinition) {
+            if (null !== $serviceIdDefinition->getClass()) {
+                break;
+            }
+            $serviceIdDefinition = $container->getDefinition($serviceIdDefinition->getParent());
+        }
+
+        return $serviceIdDefinition->getClass();
+    }
 }
@@ -12,6 +12,7 @@
 namespace Symfony\Component\Messenger\Tests\DependencyInjection;
 
 use PHPUnit\Framework\TestCase;
+use Symfony\Component\DependencyInjection\ChildDefinition;
 use Symfony\Component\DependencyInjection\Compiler\ResolveChildDefinitionsPass;
 use Symfony\Component\DependencyInjection\Compiler\ResolveClassPass;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
@@ -208,6 +209,34 @@ public function testGetClassesAndMethodsAndPrioritiesFromTheSubscriber()
         $this->assertSame(PrioritizedHandler::class, $secondHandlerDefinition->getClass());
     }
 
+    public function testRegisterAbstractHandler()
+    {
+        $container = $this->getContainerBuilder($messageBusId = 'message_bus');
+        $container->register($messageBusId, MessageBusInterface::class)->addTag('messenger.bus')->setArgument(0, []);
+
+        $container
+            ->register(DummyHandler::class, DummyHandler::class)
+            ->setAbstract(true);
+
+        $container
+            ->setDefinition($abstractDirectChildId = 'direct_child', new ChildDefinition(DummyHandler::class))
+            ->setAbstract(true);
+
+        $container
+            ->setDefinition($abstractHandlerId = 'child', new ChildDefinition($abstractDirectChildId))
+            ->addTag('messenger.message_handler');
+
+        (new MessengerPass())->process($container);
+
+        $messageHandlerMapping = $container->getDefinition($messageBusId.'.messenger.handlers_locator')->getArgument(0);
+        $this->assertHandlerDescriptor(
+            $container,
+            $messageHandlerMapping,
+            DummyMessage::class,
+            [$abstractHandlerId]
+        );
+    }
+
     /**
      * @expectedException \Symfony\Component\DependencyInjection\Exception\RuntimeException
      * @expectedExceptionMessage Invalid service "NonExistentHandlerClass": class "NonExistentHandlerClass" does not exist.