Fatal error: Uncaught Error: Class "Drupal\migrate\ProcessPluginBase" not found in /home/www/drupal8/test/modules/migrate_plus/src/Plugin/migrate/process/FileBlob.php:20 Stack trace: #0 {main} thrown in /home/www/drupal8/test/modules/migrate_plus/src/Plugin/migrate/process/FileBlob.php on line 20