Fatal error: Uncaught Error: Interface "Drupal\webform\WebformEntityReferenceManagerInterface" not found in /home/www/drupal8/test/modules/webform/src/WebformEntityReferenceManager.php:22 Stack trace: #0 {main} thrown in /home/www/drupal8/test/modules/webform/src/WebformEntityReferenceManager.php on line 22