> sometimes when I need to change the database object - view/procedure - this error is raised.
>
> Can I detect which user/transaction causing this problem?

Possibly via the Trace API, but I haven't tried.

> What can I do to not have this error?

Can be tricky in a database being in use.



--
With regards,
Thomas Steinmaurer
http://www.upscene.com/

Professional Tools and Services for Firebird
FB TraceManager, IB LogManager, Database Health Check, Tuning etc.