What backend version are you using? I seems you are using a very old version
of the backend (server) and the driver is trying to comunicate in a newer
protocol. Theres a way to change the protocol, using the connection string,
but I think it will be better to update the server to the newest version.

On 1/24/06, Antonio Rodriguez Anaya <arodriguez@dia.uned.es> wrote:
>
> Hi,
>
> Sorry, I don't have time to reply the message.
>
> Thanks for the advice. I've changed the jdbc file for the newest.
> However I have errors in the same point but the message has changed.
>
> The java error is:
>
> FATAL: Socket command type unknown
>
> And the error message in postgrsql server is:
>
> FATAL: unsupported frontend protocol
> FATAL: Socket command type unknown
>
>
> I don't know why postgresql does'nt support frontend protocol, and I
> don't know how to change that protocol.
>
> Thanks in advanced,
>
> Toni.
>
> El 19/01/2006, a las 23:06, Oliver Jowett escribió:
>
> > Antonio Rodriguez Anaya wrote:
> >> The class gets connect with postgrsql by jdbc (pg73jdbc3.jar) without
> >> problems.
> >
> > This version of the driver is essentially unmaintained, I suggest you
> > upgrade to a more recent build (later driver versions should still
> > operate correctly against a 7.3 server).
> >
> > -O
> >
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