diff --git a/core/lib/Drupal/Core/Controller/ExceptionController.php b/core/lib/Drupal/Core/Controller/ExceptionController.php
index 66a6215..59bc9fa 100644
--- a/core/lib/Drupal/Core/Controller/ExceptionController.php
+++ b/core/lib/Drupal/Core/Controller/ExceptionController.php
@@ -12,7 +12,7 @@
 use Symfony\Component\HttpFoundation\Response;
 use Symfony\Component\HttpFoundation\JsonResponse;
 use Symfony\Component\HttpKernel\HttpKernelInterface;
-use Symfony\Component\HttpKernel\Exception\FlattenException;
+use Symfony\Component\Debug\Exception\FlattenException;
 
 use Drupal\Core\ContentNegotiation;
 
@@ -42,7 +42,7 @@ public function __construct(ContentNegotiation $negotiation) {
   /**
    * Handles an exception on a request.
    *
-   * @param \Symfony\Component\HttpKernel\Exception\FlattenException $exception
+   * @param \Symfony\Component\Debug\Exception\FlattenException $exception
    *   The flattened exception.
    * @param \Symfony\Component\HttpFoundation\Request $request
    *   The request that generated the exception.
@@ -63,9 +63,9 @@ public function execute(FlattenException $exception, Request $request) {
   /**
    * Processes a MethodNotAllowed exception into an HTTP 405 response.
    *
-   * @param Symfony\Component\HttpKernel\Exception\FlattenException $exception
+   * @param \Symfony\Component\Debug\Exception\FlattenException $exception
    *   The flattened exception.
-   * @param Symfony\Component\HttpFoundation\Request $request
+   * @param \Symfony\Component\HttpFoundation\Request $request
    *   The request object that triggered this exception.
    */
   public function on405Html(FlattenException $exception, Request $request) {
@@ -75,9 +75,9 @@ public function on405Html(FlattenException $exception, Request $request) {
   /**
    * Processes an AccessDenied exception into an HTTP 403 response.
    *
-   * @param Symfony\Component\HttpKernel\Exception\FlattenException $exception
+   * @param \Symfony\Component\Debug\Exception\FlattenException $exception
    *   The flattened exception.
-   * @param Symfony\Component\HttpFoundation\Request $request
+   * @param \Symfony\Component\HttpFoundation\Request $request
    *   The request object that triggered this exception.
    */
   public function on403Html(FlattenException $exception, Request $request) {
@@ -130,9 +130,9 @@ public function on403Html(FlattenException $exception, Request $request) {
   /**
    * Processes a NotFound exception into an HTTP 404 response.
    *
-   * @param Symfony\Component\HttpKernel\Exception\FlattenException $exception
+   * @param \Symfony\Component\Debug\Exception\FlattenException $exception
    *   The flattened exception.
-   * @param Sonfony\Component\HttpFoundation\Request $request
+   * @param \Symfony\Component\HttpFoundation\Request $request
    *   The request object that triggered this exception.
    */
   public function on404Html(FlattenException $exception, Request $request) {
@@ -202,9 +202,9 @@ public function on404Html(FlattenException $exception, Request $request) {
   /**
    * Processes a generic exception into an HTTP 500 response.
    *
-   * @param Symfony\Component\HttpKernel\Exception\FlattenException $exception
+   * @param \Symfony\Component\Debug\Exception\FlattenException $exception
    *   Metadata about the exception that was thrown.
-   * @param Symfony\Component\HttpFoundation\Request $request
+   * @param \Symfony\Component\HttpFoundation\Request $request
    *   The request object that triggered this exception.
    */
   public function on500Html(FlattenException $exception, Request $request) {
@@ -270,9 +270,9 @@ public function on500Html(FlattenException $exception, Request $request) {
   /**
    * Processes an AccessDenied exception that occured on a JSON request.
    *
-   * @param Symfony\Component\HttpKernel\Exception\FlattenException $exception
+   * @param \Symfony\Component\Debug\Exception\FlattenException $exception
    *   The flattened exception.
-   * @param Symfony\Component\HttpFoundation\Request $request
+   * @param \Symfony\Component\HttpFoundation\Request $request
    *   The request object that triggered this exception.
    */
   public function on403Json(FlattenException $exception, Request $request) {
@@ -284,9 +284,9 @@ public function on403Json(FlattenException $exception, Request $request) {
   /**
    * Processes a NotFound exception that occured on a JSON request.
    *
-   * @param Symfony\Component\HttpKernel\Exception\FlattenException $exception
+   * @param \Symfony\Component\Debug\Exception\FlattenException $exception
    *   The flattened exception.
-   * @param Symfony\Component\HttpFoundation\Request $request
+   * @param \Symfony\Component\HttpFoundation\Request $request
    *   The request object that triggered this exception.
    */
   public function on404Json(FlattenException $exception, Request $request) {
@@ -298,9 +298,9 @@ public function on404Json(FlattenException $exception, Request $request) {
   /**
    * Processes a MethodNotAllowed exception that occured on a JSON request.
    *
-   * @param Symfony\Component\HttpKernel\Exception\FlattenException $exception
+   * @param \Symfony\Component\Debug\Exception\FlattenException $exception
    *   The flattened exception.
-   * @param Symfony\Component\HttpFoundation\Request $request
+   * @param \Symfony\Component\HttpFoundation\Request $request
    *   The request object that triggered this exception.
    */
   public function on405Json(FlattenException $exception, Request $request) {
@@ -316,6 +316,8 @@ public function on405Json(FlattenException $exception, Request $request) {
    * @todo This should get refactored. FlattenException could use some
    *   improvement as well.
    *
+   * @param \Symfony\Component\Debug\Exception\FlattenException $exception
+   *  The flattened exception
    * @return array
    */
   protected function decodeException(FlattenException $exception) {
diff --git a/core/tests/Drupal/Tests/Core/Controller/ExceptionControllerTest.php b/core/tests/Drupal/Tests/Core/Controller/ExceptionControllerTest.php
index 020daab..88a010d 100644
--- a/core/tests/Drupal/Tests/Core/Controller/ExceptionControllerTest.php
+++ b/core/tests/Drupal/Tests/Core/Controller/ExceptionControllerTest.php
@@ -11,7 +11,7 @@
 use Drupal\Core\Controller\ExceptionController;
 use Drupal\Tests\UnitTestCase;
 use Symfony\Component\HttpFoundation\Request;
-use Symfony\Component\HttpKernel\Exception\FlattenException;
+use Symfony\Component\Debug\Exception\FlattenException;
 
 /**
  * Tests exception controller.