Fatal error: Uncaught Error: Class "Symfony\Component\Validator\Constraint" not found in /home/www/drupal8/test/core/modules/link/src/Plugin/Validation/Constraint/LinkExternalProtocolsConstraint.php:15
Stack trace:
#0 {main}
thrown in /home/www/drupal8/test/core/modules/link/src/Plugin/Validation/Constraint/LinkExternalProtocolsConstraint.php on line 15