Fatal error: Uncaught Error: Class "Symfony\Component\CssSelector\Node\AbstractNode" not found in /opt/lampp/htdocs/forum/flarum/vendor/symfony/css-selector/Node/SpecificityAdjustmentNode.php:24 Stack trace: #0 {main} thrown in /opt/lampp/htdocs/forum/flarum/vendor/symfony/css-selector/Node/SpecificityAdjustmentNode.php on line 24