Fatal error: Uncaught Error: Class "HTMLPurifier_AttrDef_HTML_Nmtokens" not found in E:\xampp\htdocs\stms\vendor\ezyang\htmlpurifier\library\HTMLPurifier\AttrDef\HTML\Class.php:6 Stack trace: #0 {main} thrown in E:\xampp\htdocs\stms\vendor\ezyang\htmlpurifier\library\HTMLPurifier\AttrDef\HTML\Class.php on line 6