***** ViPER Guestbook is no longer supported by its developers and is not recommended for use.******
Instead, if you are a SiteGround customer you can use the Ardguest guestbook application or check the scripts listed in cPanel->Softaculous->Guest Books.
Basically if the automatic Fantastico upgrade fails you would need to restore your ViPER Guestbook from a backup and to start the upgrade process again.
ViPER Guestbook backup restore
If you have made occasional backups of you ViPER Guestbook on your local computer, which is highly recommendable, you will be able to restore the latest one.
Alternatively, the Fantastico auto-installer usually creates a full back-up of the application on your account before upgrading it. In order to learn how you can restore this backup please refer to our article about Fantastico backup restore.
You need help with an application? hostlantern is specialized in hosting and supporting more than 200 scripts. Sign up for our web hosting services and let us help you with your application, 24/7!