Fatal error: Uncaught Error: Class "Drupal\node\Plugin\migrate\source\d6\ViewModeBase" not found in /home/www/drupal8/test/core/modules/node/src/Plugin/migrate/source/d6/ViewMode.php:13 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/modules/node/src/Plugin/migrate/source/d6/ViewMode.php on line 13