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