Visual Studio 2010 Will Not Use The System's Proxy Settings

There is a new feature in Visual Studio 2010 call the extension manager. It is a great feature that seems to be sensitive to proxy servers… However, in my company I could not take benefit of the extension manager for long time. The company I work at uses a content filtering/proxy service called Web Sense. It uses some type of active directory based authentication to control access to the Internet. Although I have the proxy set in Internet Explorer via GPOs, it seemed that Visual Studio is not using those settings according to Fiddler… It turns out that the default proxy settings for .NET apps is for some reason to not use the system proxy and credentials. Visual Studio will by default ignore that proxy setting as will many other .NET applications…

I needed to configure the proxy settings in the Visual Studio config file. The section I was looking for is under <system.net>. The config file already had this section to enable IPv6.

I modified the file with this change:

The XML for copy-paste:

  <defaultProxy useDefaultCredentials="true" enabled="true">
    <proxy usesystemdefault="True" />
  </defaultProxy>

This turned out to be a fairly simple fix as these settings tells Visual Studio to use the system proxy, and to use the default credentials for that proxy.I had to close Visual Studio and re-run it again for the settings to take effect.