Re: Fatel: unsupported frientend protocol error

"David G. Johnston" <david(dot)g(dot)johnston(at)gmail(dot)com> writes:
> On Thursday, June 30, 2022, Laurenz Albe <laurenz(dot)albe(at)cybertec(dot)at> wrote:
>> On Thu, 2022-06-30 at 16:40 +0530, eswar reddy wrote:
>>> Fatel: unsupported frientend protocol 1234.5680: server supports 1.0 to
>>> 3.0

>> This is simple: upgrade the server to a supported version, ideally v14.

> Good advice regardless, but wouldn’t v14 still give that same error if some
> client tried to present protocol version 1234.5680 as the desired
> communicarion protocol?

Per src/include/libpq/pqcomm.h, that code is

#define NEGOTIATE_GSS_CODE PG_PROTOCOL(1234,5680)

So some client is running code new enough to try GSS protocol,
but the 9.6 server doesn't know what that is. You'd need v12
or later server if you don't want to see these complaints.
(But you could just ignore them.)

regards, tom lane