Fatal error: Uncaught Error: Class 'HTMLPurifier_AttrTransform' not found in C:\Web\htdocs\vendor-copia\ezyang\htmlpurifier\library\HTMLPurifier\AttrTransform\TargetBlank.php:10 Stack trace: #0 {main} thrown in C:\Web\htdocs\vendor-copia\ezyang\htmlpurifier\library\HTMLPurifier\AttrTransform\TargetBlank.php on line 10