diff --git a/core/lib/Drupal/Core/EventSubscriber/AcceptNegotiation406.php b/core/lib/Drupal/Core/EventSubscriber/AcceptNegotiation406.php
index 018eb26..4bfc942 100644
--- a/core/lib/Drupal/Core/EventSubscriber/AcceptNegotiation406.php
+++ b/core/lib/Drupal/Core/EventSubscriber/AcceptNegotiation406.php
@@ -20,6 +20,12 @@
  */
 class AcceptNegotiation406 implements EventSubscriberInterface {
 
+  /**
+   * Throws an HTTP 406 error if we get this far, which we normally shouldn't.
+   *
+   * @param \Symfony\Component\HttpKernel\Event\GetResponseForControllerResultEvent $event
+   *   The event to process.
+   */
   function onViewDetect406(GetResponseForControllerResultEvent $event) {
     $request = $event->getRequest();
     $result = $event->getControllerResult();
@@ -30,10 +36,6 @@ function onViewDetect406(GetResponseForControllerResultEvent $event) {
     // so we provide a 406 response.
     if (is_array($result) && $request->getRequestFormat() !== 'html') {
       throw new NotAcceptableHttpException('Not acceptable');
-      $result = new JsonResponse([
-        'message' => 'Not Acceptable.',
-      ], 406);
-      $event->setResponse($result);
     }
   }
 
diff --git a/core/lib/Drupal/Core/EventSubscriber/ExceptionJsonSubscriber.php b/core/lib/Drupal/Core/EventSubscriber/ExceptionJsonSubscriber.php
index 9610e8d..0aefe96 100644
--- a/core/lib/Drupal/Core/EventSubscriber/ExceptionJsonSubscriber.php
+++ b/core/lib/Drupal/Core/EventSubscriber/ExceptionJsonSubscriber.php
@@ -65,4 +65,15 @@ public function on405(GetResponseForExceptionEvent $event) {
     $event->setResponse($response);
   }
 
+  /**
+   * Handles a 406 error for JSON.
+   *
+   * @param \Symfony\Component\HttpKernel\Event\GetResponseForExceptionEvent $event
+   *   The event to process.
+   */
+  public function on406(GetResponseForExceptionEvent $event) {
+    $response = new JsonResponse(['message' => $event->getException()->getMessage()], Response::HTTP_NOT_ACCEPTABLE);
+    $event->setResponse($response);
+  }
+
 }