Fatal error: Uncaught Error: Interface "Drupal\Core\Ajax\CommandInterface" not found in /home/www/drupal8/test/core/lib/Drupal/Core/Ajax/RestripeCommand.php:16 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/lib/Drupal/Core/Ajax/RestripeCommand.php on line 16