Subject handle is Invalid

I keep getting this error when I have been closing and then trying to reopen some databases. I saw that there was an error that was fixed in
4.9.11 etc but I do not have other than 4.9.9. Can you advise what I
can change so that I can get this going again. It takes shutting down
the Firebird server on the network server to stop the error. It sounds
like something is hanging up the database on close and leaving something

(Error code 335544344)

Steve Fields