First and foremost: report the problem on github! It should not have occurred, and either points to a problem with your database, or a problem with the upgrade script itself. Please provide as much details as possible about what went wrong, any error messages and what version you were upgrading from.
Upgrading involves two things: updating the files and updating the database. If the database upgrade fails, that means that there are new files trying to read the new database, even though it wasn't updated. You have two options:
- Wait to hear a response on github,
- Revert your Form Tools files back to the previous version.
But please know that in the current state (new files + old database), Form Tools may not be able to function normally.