diff --git a/src/Symfony/Bundle/FrameworkBundle/Controller/AbstractController.php b/src/Symfony/Bundle/FrameworkBundle/Controller/AbstractController.php
index ff20fbeb65..869ade4ce8 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Controller/AbstractController.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Controller/AbstractController.php
@@ -314,7 +314,7 @@ abstract class AbstractController implements ServiceSubscriberInterface
         } else {
             $response = $render($form, $data, $request);
 
-            if ($submitted && 200 === $response->getStatusCode()) {
+            if ($response instanceof Response && $submitted && 200 === $response->getStatusCode()) {
                 $response->setStatusCode(Response::HTTP_UNPROCESSABLE_ENTITY);
             }
         }
diff --git a/src/Symfony/Bundle/FrameworkBundle/Tests/Controller/AbstractControllerTest.php b/src/Symfony/Bundle/FrameworkBundle/Tests/Controller/AbstractControllerTest.php
index c659f7e35e..ef36f3acd0 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Tests/Controller/AbstractControllerTest.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Tests/Controller/AbstractControllerTest.php
@@ -494,12 +494,12 @@ class AbstractControllerTest extends TestCase
     {
         $form = $this->createMock(FormInterface::class);
         $form->expects($this->once())->method('isSubmitted')->willReturn(true);
-        $form->expects($this->once())->method('isValid')->willReturn(true);
+        $form->expects($this->once())->method('isValid')->willReturn(false);
 
         $controller = $this->createController();
 
         $this->expectException(\TypeError::class);
-        $this->expectExceptionMessage('The "$onSuccess" callable passed to "Symfony\Bundle\FrameworkBundle\Tests\Controller\TestAbstractController::handleForm()" must return a Response, "string" returned.');
+        $this->expectExceptionMessage('The "$render" callable passed to "Symfony\Bundle\FrameworkBundle\Tests\Controller\TestAbstractController::handleForm()" must return a Response, "string" returned.');
 
         $response = $controller->handleForm(
             $form,