426 Upgrade: HTTP/3.0

• From: Jan Schaumann <jschauma@netmeister.org>
• Date: Tue, 1 Jul 2025 14:14:24 -0400
• To: ietf-http-wg@w3.org
• Message-ID: <aGQlgDZ_QDJRyf8K@netmeister.org>

Hi,

I just noticed that RFC9110 says in section 15.5.22
https://httpwg.org/specs/rfc9110.html#status.426

"Example:

HTTP/1.1 426 Upgrade Required
Upgrade: HTTP/3.0
"

Seeking an upgrade to H3 would entail a switch in
connection protocol, but further down in section 7.8,
RFC9110 also explicitly says

"The Upgrade header field only applies to switching
protocols on top of the existing connection; it cannot
be used to switch the underlying connection
(transport) protocol, nor to switch the existing
communication to a different connection. For those
purposes, it is more appropriate to use a 3xx
(Redirection) response (Section 15.4)."


So these two parts seem to contradict each other, and
the 'Upgrade' section should use a different example?

-Jan

Received on Monday, 7 July 2025 08:12:53 UTC