Fatal error: Uncaught Error: Class "HTMLPurifier_AttrDef_HTML_Nmtokens" not found in /srv/www/htdocs/moodle/lib/htmlpurifier/HTMLPurifier/AttrDef/HTML/Class.php:6 Stack trace: #0 {main} thrown in /srv/www/htdocs/moodle/lib/htmlpurifier/HTMLPurifier/AttrDef/HTML/Class.php on line 6