Fatal error: Uncaught Error: Class "Drupal\Core\Action\ActionBase" not found in /home/www/drupal8/test/core/modules/user/src/Plugin/Action/CancelUser.php:21 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/modules/user/src/Plugin/Action/CancelUser.php on line 21