Sometimes you may find that your Webmail Clients receive an error on 1 specific user, or a few when trying to access the Roundcube web mail – is Horde loading fine?

You can always try rebuilding the Roundcube database, this could be stored in sql or sqlite,

Running the following command will automatically detect what type of database roundcube is using, and start a rebuild process manually

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

This will take a while to complete depending on your server but once it’s done, you should find RoundCube loads normally again.