Hello Erland,
According to the Database Engine events and errors (0 to 999) page, error code 606 indicates:
- “Metadata inconsistency. Filegroup id %ld specified for table '%.ls' does not exist. Run DBCC CHECKDB or CHECKCATALOG.”
To diagnose the issue and get the exact corruption details, I recommend you run the following command on your database:
DBCC CHECKDB('databaseName') WITH NO_INFOMSGS, ALL_ERRORMSGS;
If the DB corruption is confirmed, the safest resolution is to restore the database from a clean backup taken before the issue occurred.