Fatal error: Uncaught Error: Class "Drupal\FunctionalTests\Update\UpdatePathTestBase" not found in /home/www/drupal8/test/core/modules/system/tests/src/Functional/Update/MenuTreeSerializationTitleTest.php:14
Stack trace:
#0 {main}
thrown in /home/www/drupal8/test/core/modules/system/tests/src/Functional/Update/MenuTreeSerializationTitleTest.php on line 14