Connection to storage server failed

The problem below appears when you attempt to use webmail to access Roundcube. Even if there is enough disk space allocated to the hosting/email account and available on the server, you still receive it.

Connection to storage server failed.
Fix to be applied is by performing cPanel updates on the server & restarting mail service.
Login to your server via SSH as root & execute the command below.
/scripts/upcp –force
Once cPanel updates are completed, restart mail server exim with command below.
/etc/init.d/exim restart

OR
service exim restart
Now try reaching Roundcube via webmail, and it should work. The aforementioned patch is only applicable if you have managed VPS hosting OR a dedicated server. If you utilize a shared hosting platform, get in touch with your web hosting provider.