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