Fatal error: Uncaught Error: Class "Drupal\views_ui\ViewFormBase" not found in /home/www/drupal8/test/core/modules/views_ui/src/ViewDuplicateForm.php:12 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/modules/views_ui/src/ViewDuplicateForm.php on line 12