Fatal error: Uncaught Error: Class "Drupal\migrate\ProcessPluginBase" not found in /home/www/drupal8/test/core/modules/field/src/Plugin/migrate/process/d6/FieldInstanceSettings.php:14
Stack trace:
#0 {main}
thrown in /home/www/drupal8/test/core/modules/field/src/Plugin/migrate/process/d6/FieldInstanceSettings.php on line 14