Fatal error: Uncaught Error: Class 'HTMLPurifier_AttrDef_URI' not found in /opt/lampp/htdocs/io.core.websocket/vendor/ezyang/htmlpurifier/library/HTMLPurifier/AttrDef/CSS/URI.php:12 Stack trace: #0 {main} thrown in /opt/lampp/htdocs/io.core.websocket/vendor/ezyang/htmlpurifier/library/HTMLPurifier/AttrDef/CSS/URI.php on line 12