Fatal error: Uncaught Error: Class "Drupal\node\Plugin\migrate\source\d6\ViewModeBase" not found in /home/www/drupal8/test/core/modules/field/src/Plugin/migrate/source/d6/FieldInstancePerViewMode.php:15 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/modules/field/src/Plugin/migrate/source/d6/FieldInstancePerViewMode.php on line 15