Fatal error: Uncaught Error: Interface "League\CommonMark\Exception\CommonMarkException" not found in /opt/lampp/htdocs/forum/flarum/vendor/league/commonmark/src/Extension/FrontMatter/Exception/InvalidFrontMatterException.php:18 Stack trace: #0 {main} thrown in /opt/lampp/htdocs/forum/flarum/vendor/league/commonmark/src/Extension/FrontMatter/Exception/InvalidFrontMatterException.php on line 18