We recently migrated WHMCS to latest CentOS 7 server with cPanel. The WHMCS ClientArea showed White screen when “Client logins were used”. We found that the server had MySQL strict mode enabled which was causing this problem.
I disabled MySQL strict mode as below :
Edited /usr/my.cnf and changed below value :
sql_mode=NO_ENGINE_SUBSTITUTION,NO_AUTO_CREATE_USER
Restarted MySQL :
/scripts/restartsrv mysql
voila this worked…… earlier I was trying to change sql_mode under /etc/my.cnf however found MySQL is using different location /usr/my.cnf