Fatal error: Uncaught Error: Interface "React\Promise\PromiseInterface" not found in /opt/lampp/htdocs/forum/flarum/vendor/react/promise/src/Internal/FulfilledPromise.php:14 Stack trace: #0 {main} thrown in /opt/lampp/htdocs/forum/flarum/vendor/react/promise/src/Internal/FulfilledPromise.php on line 14