diff --git a/core/modules/field_ui/src/Tests/ManageFieldsTest.php b/core/modules/field_ui/src/Tests/ManageFieldsTest.php
index 2255f29..fb4a5e6 100644
--- a/core/modules/field_ui/src/Tests/ManageFieldsTest.php
+++ b/core/modules/field_ui/src/Tests/ManageFieldsTest.php
@@ -627,6 +627,18 @@ public function testExternalDestinations() {
     // The external redirect should not fire.
     $this->assertUrl('admin/structure/types/manage/article/fields/node.article.body/storage', $options);
     $this->assertResponse(400);
+
+    foreach ($this->assertions as $id => $assertion) {
+      if ($assertion['status'] === 'exception') {
+        // Ensure that the right error is thrown.
+        $this->assertEqual('User error', $assertion['message_group']);
+        $this->assertEqual('Redirects to external URLs are not allowed by default, use \Drupal\Core\Routing\RedirectResponseAllowExternalUrl for it', $assertion['message']);
+        // Finally remove that exception entry in order to not fail the test
+        // itself.
+        unset($this->assertions[$id]);
+        $this->deleteAssert($assertion['message_id']);
+      }
+    }
   }
 
   /**