Fatal error: Uncaught Error: Class "Drupal\Tests\file\Functional\FileManagedTestBase" not found in /home/qcsvlel/www/core/modules/file/tests/src/Functional/SaveUploadFormTest.php:19 Stack trace: #0 {main} thrown in /home/qcsvlel/www/core/modules/file/tests/src/Functional/SaveUploadFormTest.php on line 19