Re: [squid-users] http-returncode 417 and POST-request

From: Amos Jeffries <>
Date: Mon, 08 Nov 2010 20:24:59 +1300

On 08/11/10 19:59, Tom Tux wrote:
> Hi
> I have servers, which needs to connect to with a POST-request:
> xx,xx.xx.xx NONE/417 4362 POST -
> NONE/- text/html
> This POST-request will fail (417-error), until I configure
> "ignore_expect_100 on" in squid.conf (using squid 3.1.6).
> Are there known problems / issues, with enabling the parameter
> "ignore_expect_100"? What could be the reason for this 417-error?

The client software is broken. The 417 reply indicates that the 1xx
feature REQUIRED by the client is going to fail if used. They are
supposed to re-try the request with HTTP/1.0-compatible features after
getting a 417.

It's fairly safe to set it to ignore. What will happen is that Squid
drops the 1xx messages and the broken client software which asked for
them will wait for an unknown (long) time before either dying or
continuing anyway.
  The downside is that lag for the client and lots of resources held up
waiting for it to stop waiting for something that is never going to happen.
  If there is any genuine HTTP/1.0-only software in the chain it will
barf on the 100 status message and kill the connection regardless of
what Squid does.

> Is there another way in squid.conf allowing these servers the
> POST-request? I tried with defining a separate acl (method POST), but
> this did not worked. The only way, the servers were able to connect to
> (POST) was with defining the "ignore_expect_100"-option.

Alternatively 3.2 (beta) now supports 1xx messages and will not generate
the 417. This is no guarantee that other software wont generate it.


Please be using
   Current Stable Squid 2.7.STABLE9 or 3.1.9
   Beta testers wanted for
Received on Mon Nov 08 2010 - 07:25:05 MST

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