diff --git a/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php b/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php
index b69254687c6d..00412e5c6805 100644
--- a/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php
+++ b/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php
@@ -1631,11 +1631,14 @@ private function registerAnnotationsConfiguration(array $config, ContainerBuilde
 
         $loader->load('annotations.php');
 
+        // registerUniqueLoader exists since doctrine/annotations v1.6
         if (!method_exists(AnnotationRegistry::class, 'registerUniqueLoader')) {
+            // registerLoader exists only in doctrine/annotations v1
             if (method_exists(AnnotationRegistry::class, 'registerLoader')) {
                 $container->getDefinition('annotations.dummy_registry')
                     ->setMethodCalls([['registerLoader', ['class_exists']]]);
             } else {
+                // remove the dummy registry when doctrine/annotations v2 is used
                 $container->removeDefinition('annotations.dummy_registry');
             }
         }
diff --git a/src/Symfony/Bundle/FrameworkBundle/Resources/config/annotations.php b/src/Symfony/Bundle/FrameworkBundle/Resources/config/annotations.php
index 8bb408e2aba6..33a2f46989de 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Resources/config/annotations.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Resources/config/annotations.php
@@ -26,7 +26,7 @@
         ->set('annotations.reader', AnnotationReader::class)
             ->call('addGlobalIgnoredName', [
                 'required',
-                service('annotations.dummy_registry')->ignoreOnInvalid(), // dummy arg to register class_exists as annotation loader only when required
+                service('annotations.dummy_registry')->nullOnInvalid(), // dummy arg to register class_exists as annotation loader only when required
             ])
 
         ->set('annotations.dummy_registry', AnnotationRegistry::class)