Fatal error: Uncaught Error: Class "Drupal\Core\Action\ConfigurableActionBase" not found in /home/www/drupal8/test/core/modules/user/src/Plugin/Action/ChangeUserRoleBase.php:17 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/modules/user/src/Plugin/Action/ChangeUserRoleBase.php on line 17