In some circumstances, you may find that Roundcube loads with the following error message:
DATABASE ERROR: CONNECTION FAILED!
Unable to connect to the database!
Please contact your server-administrator.
And the Roundcube databases in /home/$user/etc/$domain are not present.
The issue is most often caused by the cPanel PHP-FPM process hanging onto connections. Sending PHP-FPM a hard restart generally addresses the problem.
To restart the process, we recommend running these commands: