Message contents do not agree with length in message type "Z"

I'm using the libpq interface to PostgreSQL (8.2.5) in one of our apps,
and I'm having an issue with receiving the error message: message contents do not agree with length in message type "Z"
Does anybody have any idea what this message means and how to fix this ?

Thanks,

That doesn't sound like a Postgres error message, more like an application level validation problem.

And you should really upgrade to a more recent version.

I saw this message "message contents do not agree with length in message type" in file fe-protocol3.c
In my app, this message produce by PQerrorMessage(conn)
So, I think that it must be a Postgres error, but I could not understand why it occur !