Webmail login Error

Could you also check in /var/cpanel/horde/log/errors for the errors showing there? If Roundcube is likewise having an issue, there's an error log for it at /var/cpanel/roundcube/log/errors that would be helpful. Those logs might provide more details on specifically what's happening.

Also, is this only impacting one email account on one domain, on all email accounts on one domain, or on all emails accounts on all domains?

You might try running /scripts/fullhordereset --force in root SSH, but it's better to see what the set errors are first to track down the specific issue here. It seems to be an authentication issue for the account, which usually points to either incorrect permissions or ownership on /home/username/etc/ folder (or the folders or files within that folder). If all domains are impacted, though, then it isn't incorrect permissions but instead something else.

 

Here are the permissions for each level of the /home/username/etc per one of my own accounts:

/home/user/etc permissions

Code:

drwxr-x---   6 user mail   4.0K Jan 28 15:27 etc

/home/user/etc/domain.com permissions

Code:

drwxr-x---   5 user mail  4.0K Jul  9 12:50 domain.com

/home/user/etc/domain.com permissions inside the folder

Code:

drwx--x--x  4 user user 4.0K Apr 10 15:52 admin
drwx--x--x  3 user user 4.0K Apr 10 15:52 cpacct
-rw-r--r--  1 user mail   152 Feb 24 13:23 passwd
-rw-r--r--  1 user user 1.9K Feb 24 13:23 passwd,v
drwxr-x---  2 user mail  4.0K Feb 24 13:24 @pwcache
-rw-r--r--  1 user user   33 Feb 24 13:23 quota
-rw-r--r--  1 user user  387 Feb 24 13:23 quota,v
-rw-r-----  1 user mail   107 Apr 10 16:00 shadow
-rw-r-----  1 user user 2.0K Feb 24 13:23 shadow,v

Please note the ownership permissions really matter quite a bit. The /home/user/etc, /home/user/etc/domain.com and /home/user/etc/domain.com/passwd, @pwcache and shadow all have user:mail permissions not user:user permissions.

If your permissions and ownership are correct for each of these, then also cat the /home/user/etc/domain.com/passwd file to see if the accounts are listed there. Sometimes they are missing. If they are indeed missing, then you will have to remove and re-create the accounts to restore the data. You can copy the /home/user/mail/domain.com/emailuser folder to a backup before removing the account, then restore the contents of that folder so that you don't lose the data, though.