A user who has been installed for literally decades has suddenly gotten this message. This is a FE/BE but there is only one user involved and no network. When he gets this message, he is done. He must exit the database entirely. He even has resorted to rebooting to make the error message go away.
Why this problem has developed in a mature database is surprising, but how to fix it is the question. Should I be more diligent in closing tables and forms? The form that generates the error is a somewhat complex one with a few subforms attached, but nothing exceptional.
Any advice is welcome.