got some reference from: https://github.com/osTicket/osTicket/issues/2298jdelhome3578 commented on Sep 10, 2015thanks to jdelhome3578, workaround before it fixed the problem, try to adjust tuning for mysql cache and APCu and Zend Opcache listed in Dashboard->Informationnow is more recent to showing normal than error for not loading full header pagethanks