Fatal error: Uncaught Error: Class "Drupal\migrate\ProcessPluginBase" not found in /home/www/drupal8/test/core/modules/block/src/Plugin/migrate/process/BlockPluginId.php:19
Stack trace:
#0 {main}
thrown in /home/www/drupal8/test/core/modules/block/src/Plugin/migrate/process/BlockPluginId.php on line 19