07 Jun 2012

imageWith Visual Studio 2012 there is an increase importance placed on the Extension Manager component, not only does it provide a great integrated experience to the Visual Studio gallery for downloading and updating extensions but it will also be used to delivery updates for Visual Studio itself!

At work it would constantly fail to work with error 417 – expectation failed, so working with our facilities team we were able to identify the problem as an issue with the proxy server we use, Squid.

Squid seems unable to handle the HTTP status code 100, and will then fail with the error 417. To solve this you simple need to add the following to your squid.conf file: ignore_expect_100 on


Graham's picture

You can also turn off the 100-expect behaviour in Visual Studio.

If you edit devenv.com.config to have the following additional setting (only without the <br>'s - can't get the webpage quoting right..):

            <ipv6 enabled="true"/>
            <servicePointManager expect100Continue="false" /> <!-- add this setting to stop 417 errors -->

This setting has allowed me to get the extension manager in VS2010 and VS2012 to work without any input from our ITto alter the proxy settings.

Visitor's picture

devenv.com.config this file does not exist

hype8912's picture

The name of the file is devenv.exe.config. The file is located at the following path.

"C:\Program Files (x86)\Microsoft Visual Studio 11.0\Common7\IDE\devenv.exe.config"

ShadyH's picture

nicely spotted. looks like some time not well spent for ya

i opted for editing squid.conf, did a kill -HUP on it to refresh config and the retry button immediately worked in extension manager. cheers for sharing

Graham's picture

Sorry, looking at it again ... you're right, devenv.com.config doesn't exists. Its actually devenv.exe.config

Roeland's picture

Graham, that worked superb. Thank you very much!

One note if people get write error trouble: you need to edit this as administrator, not as a local user.

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