Fatal error: Uncaught Error: Interface "GuzzleHttp\Promise\PromiseInterface" not found in /opt/lampp/htdocs/forum/flarum/vendor/guzzlehttp/promises/src/FulfilledPromise.php:15 Stack trace: #0 {main} thrown in /opt/lampp/htdocs/forum/flarum/vendor/guzzlehttp/promises/src/FulfilledPromise.php on line 15