diff -u b/core/modules/user/lib/Drupal/user/EntityAuthorInterface.php b/core/modules/user/lib/Drupal/user/EntityAuthorInterface.php
--- b/core/modules/user/lib/Drupal/user/EntityAuthorInterface.php
+++ b/core/modules/user/lib/Drupal/user/EntityAuthorInterface.php
@@ -5,7 +5,7 @@
  * Contains \Drupal\user\EntityAuthorInterface.
  */
 
-namespace Drupal\Core\Entity;
+namespace Drupal\user;
 
 /**
  * Defines a common interface for entities that have an author or owner.