Often errors like these can be addressed through Clear the Cache.
You have to be careful when restoring a backup from a different OH version. If it was a full backup, it means you got the cache and tmp folders too. As a result you overwrote the 4.1 stuff with 3.x stuff and they of course the 3.x stuff can’t run on 4.1.
Also note that most people have reported that restoring a 3.x backup to a 4.0/4.1 does work, this is not always guaranteed to work.
Don’t forget to run the upgrade tool before running OH for the first time after restoring the backup.
The normal most likely to work approach is to:
- Backup the old full system, upgrade the old to 4.1, take the backup, then restore the 4.1 backup to the 4.1 instance; if you run into trouble restore the backup you took at the beginning.
- Backup OH, install 3.4 on the new machine, restore the OH backup, then do an in place upgrade to 4.1.