Robert MacLean
7 June 2012
With 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