diff --git a/core/lib/Drupal/Core/EventSubscriber/ExceptionJsonSubscriber.php b/core/lib/Drupal/Core/EventSubscriber/ExceptionJsonSubscriber.php
index dc4bf00..d80384c 100644
--- a/core/lib/Drupal/Core/EventSubscriber/ExceptionJsonSubscriber.php
+++ b/core/lib/Drupal/Core/EventSubscriber/ExceptionJsonSubscriber.php
@@ -3,7 +3,6 @@
 namespace Drupal\Core\EventSubscriber;
 
 use Symfony\Component\HttpFoundation\JsonResponse;
-use Symfony\Component\HttpFoundation\Response;
 use Symfony\Component\HttpKernel\Event\GetResponseForExceptionEvent;
 
 /**
@@ -28,12 +27,12 @@ protected static function getPriority() {
   }
 
   /**
-   * Handles all 400 errors for JSON.
+   * Handles all 4xx errors for JSON.
    *
    * @param \Symfony\Component\HttpKernel\Event\GetResponseForExceptionEvent $event
    *   The event to process.
    */
-  public function on400(GetResponseForExceptionEvent $event) {
+  public function on4xx(GetResponseForExceptionEvent $event) {
     /** @var \Symfony\Component\HttpKernel\Exception\HttpExceptionInterface $exception */
     $exception = $event->getException();
     $response = new JsonResponse(['message' => $event->getException()->getMessage()], $exception->getStatusCode());
diff --git a/core/lib/Drupal/Core/EventSubscriber/HttpExceptionSubscriberBase.php b/core/lib/Drupal/Core/EventSubscriber/HttpExceptionSubscriberBase.php
index 84fe421..b062b97 100644
--- a/core/lib/Drupal/Core/EventSubscriber/HttpExceptionSubscriberBase.php
+++ b/core/lib/Drupal/Core/EventSubscriber/HttpExceptionSubscriberBase.php
@@ -92,7 +92,7 @@ public function onException(GetResponseForExceptionEvent $event) {
       $method = 'on' . $exception->getStatusCode();
       // Keep just the leading number of the status code to produce either a
       // on400 or a 500 method callback.
-      $method_fallback = 'on' . floor($exception->getStatusCode() / 100) . '00';
+      $method_fallback = 'on' . floor($exception->getStatusCode() / 100) . 'xx';
       // We want to allow the method to be called and still not set a response
       // if it has additional filtering logic to determine when it will apply.
       // It is therefore the method's responsibility to set the response on the