Roundcube error :SERVICE CURRENTLY NOT AVAILABLE! Error No. [500]

We were facing one of the following problem:

[wpfmb type=’error’ theme=2]SERVICE CURRENTLY NOT AVAILABLE!
Error No. [500][/wpfmb]

This problem occurs because of Roundcube database structure has not updated properly.

There is a very simple command to resolve the issue:

1) Login to the server as root

2) Just run the following command on a cPanel server.

/usr/local/cpanel/bin/update-roundcube-sqlite –force

This command will update the round cube forcefully on the server and should now resolve the issue.