The main thing though is that these UDFs work ok in Firebird 2.5. I have also developed a UDF (DLL) in Delphi, and that does not work either. It used to in 2.5 (still does). I thought it better to mention the FreeAdhocUDF issue otherwise it would be my fault that my own UDF does not work!

There is obviously something different about V3 that is stopping some UDFs from working. In my own limited experience, it is stopping ALL UDFs from working.

And this is not a trivial problem. I have spent days trying to remove UDFs from my existing 2.5 version databases, and it is not an easy job.