Roundcube Log Location (cPanel)
When trying to diagnose Roundcube errors the log files can tell you exactly whats going on. Below are the locations of log files that may be useful to diagnose Roundcube errors on cPanel/WHM servers.
Roundcube-specific Logs
/var/cpanel/roundcube/errors
/var/cpanel/roundcube/sendmail
Additional Useful Logs
/usr/local/cpanel/logs/access_log
/usr/local/cpanel/logs/error_log
/usr/local/cpanel/logs/login_log