Date: Thu, 23 May 2024 09:06:49 +0200
From: "Peter J. Holzer" <hjp-pgsql@hjp.at>
To: pgsql-general@postgresql.org
Subject: expected authentication request from server, but received H
Message-ID: <20240523070649.7j6r2lidqrmhmr3o@hjp.at>
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One of our users reports getting the error message

"expected authentication request from server, but received H"

when trying to connect to the database.

I have confirmed that they do indeed connect to the database and not
some other service and in Wireshark it looks like the TLS handshake
succeeds.

Server is PostgreSQL 15.7 (Ubuntu 15.7-1.pgdg22.04+1)
I haven't been able to find out what client version they are using yet,
but I suspect it's quite old.

We've been on 15.x for quite a while now and it did work until at least
a month ago, so I wouldn't expect an incompatible protocol change,
however, I think the upgrade from 15.6 to 15.7 was just last week, so
maybe something changed between these minor versions?

I'm especially intrigued by "received H". According to
https://www.postgresql.org/docs/current/protocol-message-formats.html
Byte1('H') could mark a Copy Out response or a Flush command. Both don't
make sense in that context.

        hp

--=20
   _  | Peter J. Holzer    | Story must make more sense than reality.
|_|_) |                    |
| |   | hjp@hjp.at         |    -- Charles Stross, "Creative writing
__/   | http://www.hjp.at/ |       challenge!"

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