Fatal error: Uncaught Error: Class "League\OAuth2\Client\Grant\AbstractGrant" not found in /opt/lampp/htdocs/forum/flarum/vendor/league/oauth2-facebook/src/Grant/FbExchangeToken.php:5 Stack trace: #0 {main} thrown in /opt/lampp/htdocs/forum/flarum/vendor/league/oauth2-facebook/src/Grant/FbExchangeToken.php on line 5