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Re: ALPN - HTTP/2 stream 0 was not closed cleanly: PROTOCOL_ERROR

From: Daniel Stenberg via curl-users <curl-users_at_lists.haxx.se>
Date: Tue, 5 Jul 2022 23:27:49 +0200 (CEST)

On Tue, 5 Jul 2022, Robert Wolf via curl-users wrote:

> We can replicate the problem using curl directly to server without CF.

Which curl version, using which nghttp2 version on what platform? And it would
also help if you could record a failing HTTP/2 TCP stream with wireshark.

> I have read the man curl page and found the option --no-alpn. Using both
> options --http2 and --no-alpn the file is complete. So there must be
> something with ALPN in HTTP2.

I actually think that's rather a red herring/coincidence. ALPN is just a way
to select h2, once h2 has been selected and is being transfered, there's
nothing left from the alpn selection.

> Do you have any idea, how to test or prove the problem is on the server?
> There is problem with CURL and Cloudflare, but direct connection from
> Firefox (and other browsers) is OK.

I think you see a problem with the h2 implementation in the curl version you
use. The browsers have different h2 implementations and don't suffer from
this.

I also suspect that a more modern version of curl doesn't support of this
problem, but that's so far just a wild guess on my behalf.

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Received on 2022-07-05