WCF::handleException() Unhandled exception: Class 'wcf\util\FileUtil' not found

#0 /mnt/web001/d2/39/57512039/htdocs/rahmenbauforum/wcf/global.php(25): wcf\system\WCF->__construct()
#1 /mnt/web001/d2/39/57512039/htdocs/rahmenbauforum/global.php(13): require_once('/mnt/web001/d2/...')
#2 /mnt/web001/d2/39/57512039/htdocs/rahmenbauforum/index.php(9): require_once('/mnt/web001/d2/...')
#3 {main}