core/modules/rest/src/RequestHandler.php | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/core/modules/rest/src/RequestHandler.php b/core/modules/rest/src/RequestHandler.php
index c6430e0..7443537 100644
--- a/core/modules/rest/src/RequestHandler.php
+++ b/core/modules/rest/src/RequestHandler.php
@@ -143,9 +143,13 @@ protected function getResponseFormat(RouteMatchInterface $route_match, Request $
       if (!empty($acceptable_content_type_formats)) {
         return $acceptable_content_type_formats[0];
       }
-      else {
+      elseif (!empty($acceptable_request_formats)) {
         return $acceptable_request_formats[0];
       }
+      // Sometimes, there are no acceptable formats, e.g. DELETE routes.
+      else {
+        return NULL;
+      }
     }
   }
 
@@ -174,8 +178,9 @@ public function csrfToken() {
    *   The response from the REST resource.
    * @param \Symfony\Component\Serializer\SerializerInterface $serializer
    *   The serializer to use.
-   * @param string $format
-   *   The response format.
+   * @param string|null $format
+   *   The response format, or NULL in case the response does not need a format,
+   *   for example for the response to a DELETE request.
    *
    * @return \Drupal\rest\ResourceResponse
    *   The altered response.