You might receive this error if your database has been upgraded to the new TntMPD 3.0 format, but you're trying to open it from TntMPD 2.1 or older. If you suspect your spouse or team mate may have upgraded the database to TntMPD 3.0, check to see if you're running an older version. Under the Help menu, click on About to see what version you're running.
Or you might receive this error because your database file has been corrupted. For guidance on how to recover a corrupted database, click here.