Sometimes, errors like the one you saw can be spurious, but unfortunately in this case there are signs of low level corruption in your database.
This type of error is extremely rare for us and not one that we see often. Our database infrastructure is designed specifically to prevent this type of corruption, and we don’t take this class of issue lightly.
We’ve traced a few reports like this in the past to hard drive integrity issues but generally speaking, this means that Roon is reading information from your hard drive that is different from what was originally written, and the database is now unable to load properly.
If you’ve been making regular backups, my advice would be to install Roon fresh on your Core machine, and roll back to one of your backups.
You can reinstall the Roon app on your SonicTransporter by uninstalling Roon and reinstalling it via the SonicTransporter Web Interface. Following the reinstall, I would restore the database from at least a week before this issue started to occur.
If the database loads properly, your edits, playlists, tags, etc should be intact, and we can confirm everything is performing properly once it’s been restored.
If you do not have any backups, unfortunately you will need to start with a fresh database.
Again, this class of issue is extremely rare for us and you have our apologies for the trouble here.