This is already solved with a workaround (removing offline databases) but would just like to add this to the forms if anyone else gets this error.
I have been scratching my head for a while now with surebackup failing on SQL server, and opened a ticket (Case # 01846817).
Just confirmed that the SQL-VM's that are failing our surebackup with error 6 all had offline databases.
This was no problem with previous version of veeam who "just" used the Veeam.Backup.ConnectionTester.exe to test connectivity to port 1433.
But after the introduction of Veeam.Backup.SqlChecker.vbs this causes the application script to fail.
Detaching the DB’s OR bringing them online again (and backing up again) will make surebackup return a scucess for that SQL server.
However it is not that important to have the DB's offline, but sometimes, it can be practical.
Meaning that the following surebackup will fail.
I would like to see that surebackup did not FAIL on offline databases, because that is their state also in production.
So the result is expected. Off cause since I now know this, I could make custom versions of Veeam.Backup.SqlChecker.vbs for the servers with offline databases and skip checking these databases, but that means “micro managing”.
However i would say that if the databae is offline the script should just ignore it. At least not throw an error. Because you are not able/supposed to connect to the DB even in production.
I don't know what Veeam view on this.