diff --git a/core/lib/Drupal/Core/EventSubscriber/DefaultExceptionHtmlSubscriber.php b/core/lib/Drupal/Core/EventSubscriber/DefaultExceptionHtmlSubscriber.php
index cb5cd28..e3ec321 100644
--- a/core/lib/Drupal/Core/EventSubscriber/DefaultExceptionHtmlSubscriber.php
+++ b/core/lib/Drupal/Core/EventSubscriber/DefaultExceptionHtmlSubscriber.php
@@ -16,6 +16,7 @@
 use Symfony\Component\HttpFoundation\Response;
 use Symfony\Component\HttpKernel\Event\GetResponseForExceptionEvent;
 use Symfony\Component\HttpKernel\HttpKernelInterface;
+use Symfony\Component\HttpKernel\Exception\HttpExceptionInterface;
 
 /**
  * Exception subscriber for handling core default HTML error pages.
@@ -117,6 +118,7 @@ public function on404(GetResponseForExceptionEvent $event) {
    */
   protected function makeSubrequest(GetResponseForExceptionEvent $event, $url, $status_code) {
     $request = $event->getRequest();
+    $exception = $event->getException();
 
     if (!($url && $url[0] == '/')) {
       $url = $request->getBasePath() . '/' . $url;
@@ -148,7 +150,9 @@ protected function makeSubrequest(GetResponseForExceptionEvent $event, $url, $st
         $response->setStatusCode($status_code);
 
         // Persist any special HTTP headers that were set on the exception.
-        $response->headers->add($event->getException()->getHeaders());
+        if ($exception instanceof HttpExceptionInterface) {
+          $response->headers->add($exception->getHeaders());
+        }
 
         $event->setResponse($response);
       }