I have had this same problem which I think started after I installed cwp_2fa and run centos 7 then did a centos 7 update. After I removed the cwp_2fa I now have a bigger problem 404 page index is missing. /login/index.php
I did not have login access so reinstalling 2fa was never completely reinstalled since i can't make key. The cache file or what ever it is is not generated Xxxxxxxxxxxxxxxx.php is missing. Also permissions denied in this directory /usr/local/cwpsrv/htdocs/admin
run sh /scripts/update_cwp won't fix it.