Fatal error: Uncaught Error: Class "Drupal\webform\Element\WebformManagedFileBase" not found in /home/www/drupal8/test/modules/webform/src/Element/WebformAudioFile.php:10 Stack trace: #0 {main} thrown in /home/www/drupal8/test/modules/webform/src/Element/WebformAudioFile.php on line 10