User login - errors

I am unable to login as a user.

When I use https://server:2083/user/ I get "502 Bad Gateway cwpsrv" (Admin - List Accounts - User auto login)

When I use https://server:2083/ , I am able to enter username / password but get error "Failed" (Red - rt top corner)

When I use https://domain:2083/ , I am able to enter username / password but get error "Failed" (Red - rt top corner)

Please suggest. Also where can I check the logs? I tried looking at

/usr/local/apache/logs (main logs)
/usr/local/apache/domlogs

Update

I have noticed that for some users there is no problem

Only for few users, I have issue

Look into the log file:
/usr/local/cwpsrv/logs/error_log

What version of Centos do you have installed?