premium v18.2 11 users, Server 2012 R2/Sql Server 2014 SP2. backed up their 3 databases, uninstalled 18.2, rebooted. Installed 20.1 and opened/verified all 3 databases, checked actdiag and all databases were there and ok. Even ran databases maintenance on one of them.
Installed first user with same process, the first time the database on the server was accessed, user got message that they couldn't access the database. when I looked in actdiag, it was in recover mode.
called tech support, they couldn't recover the ADF via actdiag, had to restore from backup.
This happened to all 3 databases! once I restored from backup, all users accessed and the databases didn't go into recover mode.
Thank someone I did backups before starting the process.
Yes, databases have long history of Act, still they have always upgraded thru the years without problem. Though I believe one of the databases is newer, within the past 4/5 years.
From my experience:
problem is not version-specific, happened to me several times in the last 2-3 years. Rebooting the server and waiting for 10 minutes solved the problem for my in all cases. The SQL server sometimes seems to need A LOT OF time to correctly provide access to databases after an ACT! update / database update.