ASP.NET : HTTP Error 407 Proxy authentication error

If you have to develop behind a proxy, (I hate the @#$% things) you are pretty much guaranteed to get this error.

The solution is to add the following to the web.config.

<configuration>
  <system.net>
    <defaultproxy enabled="true" usedefaultcredentials="true">
      <proxy bypassonlocal="True" usesystemdefault="True">
    </proxy></defaultproxy>
  </system.net>
</configuration>

This specifies that there is a proxy, it uses your default Windows credentials to authenticate, bypasses the proxy for local addresses and uses the standard IE proxy defaults.

Problem solved.

Enjoy!