Installation über iPad bleibt stehen

 Error Type:
wcf\system\exception\ErrorException
Error Message:
Use of undefined constant SESSION_ENABLE_VIRTUALIZATION - assumed 'SESSION_ENABLE_VIRTUALIZATION'
File:
*/lib/system/WCF.class.php (322)
Stack Trace:
#0 */lib/data/session/Session.class.php (31):
wcf\system\WCF::handleError(8, 'Use of undefined constant SESSION_ENABLE_VIRTUALIZATION - assumed \'SESSION_ENABLE_VIRTUALIZATION\'', '*/lib/data/session/Session.class.php', 31, [ ])
#1 */../../../../../../[internal function] (?):
wcf\data\session\Session::supportsVirtualSessions()
#2 */lib/system/session/SessionHandler.class.php (231):
call_user_func([ 0 => , 1 => ])
#3 */lib/system/session/ACPSessionFactory.class.php (34):
wcf\system\session\SessionHandler->load('wcf\\data\\session\\SessionEditor', '')
#4 */lib/system/WCF.class.php (374):
wcf\system\session\ACPSessionFactory->load()
#5 */lib/system/WCF.class.php (165):
wcf\system\WCF->initSession()
#6 */global.php (13):
wcf\system\WCF->__construct()
#7 */index.php (8):
require_once('*/global.php')