diff --git a/core/lib/Drupal/Core/EventSubscriber/AuthenticationSubscriber.php b/core/lib/Drupal/Core/EventSubscriber/AuthenticationSubscriber.php
index 62f5486..929dc7a 100644
--- a/core/lib/Drupal/Core/EventSubscriber/AuthenticationSubscriber.php
+++ b/core/lib/Drupal/Core/EventSubscriber/AuthenticationSubscriber.php
@@ -96,7 +96,7 @@ public function onKernelRequestFilterProvider(GetResponseEvent $event) {
     if (isset($this->filter) && $event->getRequestType() === HttpKernelInterface::MASTER_REQUEST) {
       $request = $event->getRequest();
       if ($this->authenticationProvider->applies($request) && !$this->filter->appliesToRoutedRequest($request, TRUE)) {
-        throw new AccessDeniedHttpException();
+        throw new AccessDeniedHttpException('Access denied in this route.');
       }
     }
   }
diff --git a/core/modules/rest/src/Plugin/rest/resource/EntityResource.php b/core/modules/rest/src/Plugin/rest/resource/EntityResource.php
index 63e121a..ed2ecae 100644
--- a/core/modules/rest/src/Plugin/rest/resource/EntityResource.php
+++ b/core/modules/rest/src/Plugin/rest/resource/EntityResource.php
@@ -106,7 +106,7 @@ public static function create(ContainerInterface $container, array $configuratio
   public function get(EntityInterface $entity) {
     $entity_access = $entity->access('view', NULL, TRUE);
     if (!$entity_access->isAllowed()) {
-      throw new AccessDeniedHttpException('The current user does not have access to view the requested entity.');
+      throw new AccessDeniedHttpException('The current user does not have access to view the entity type {$entity->getEntityTypeId()} of bundle {$entity->bundle()}.');
     }
 
     $response = new ResourceResponse($entity, 200);
diff --git a/core/modules/rest/tests/src/Functional/BasicAuthResourceTestTrait.php b/core/modules/rest/tests/src/Functional/BasicAuthResourceTestTrait.php
index 344368e..00e205e 100644
--- a/core/modules/rest/tests/src/Functional/BasicAuthResourceTestTrait.php
+++ b/core/modules/rest/tests/src/Functional/BasicAuthResourceTestTrait.php
@@ -32,7 +32,6 @@ protected function getAuthenticationRequestOptions($method) {
    * {@inheritdoc}
    */
   protected function assertResponseWhenMissingAuthentication(ResponseInterface $response, $message = '') {
-    // 401 errors always have the same message for BasicAuth
     $this->assertResourceErrorResponse(401, 'No authentication credentials provided.', $response);
   }
 
diff --git a/core/modules/rest/tests/src/Functional/EntityResource/EntityResourceTestBase.php b/core/modules/rest/tests/src/Functional/EntityResource/EntityResourceTestBase.php
index 76d974e..23cea54 100644
--- a/core/modules/rest/tests/src/Functional/EntityResource/EntityResourceTestBase.php
+++ b/core/modules/rest/tests/src/Functional/EntityResource/EntityResourceTestBase.php
@@ -333,7 +333,7 @@ public function testGet() {
     // response.
     if (static::$auth) {
       $response = $this->request('GET', $url, $request_options);
-      $this->assertResponseWhenMissingAuthentication($response, 'The current user does not have access to view the requested entity.');
+      $this->assertResponseWhenMissingAuthentication($response, "Authentication credentials required to see the requested entity.");
     }
 
     $request_options = NestedArray::mergeDeep($request_options, $this->getAuthenticationRequestOptions('GET'));
diff --git a/core/modules/rest/tests/src/Functional/ResourceTestBase.php b/core/modules/rest/tests/src/Functional/ResourceTestBase.php
index 40f5950..f1f0458 100644
--- a/core/modules/rest/tests/src/Functional/ResourceTestBase.php
+++ b/core/modules/rest/tests/src/Functional/ResourceTestBase.php
@@ -180,7 +180,7 @@ protected function provisionResource($resource_type, $formats = [], $authenticat
   /**
    * Verifies the error response in case of missing authentication.
    */
-  abstract protected function assertResponseWhenMissingAuthentication(ResponseInterface $response, $message = '');
+  abstract protected function assertResponseWhenMissingAuthentication(ResponseInterface $response);
 
   /**
    * Asserts normalization-specific edge cases.