Fatal error: Uncaught Error: Class "Drupal\Component\Diff\Engine\DiffOp" not found in /home/www/drupal8/test/core/lib/Drupal/Component/Diff/Engine/DiffOpAdd.php:10 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/lib/Drupal/Component/Diff/Engine/DiffOpAdd.php on line 10