Did you ever had the following error when you tried to connect to Team Foundation Server(TFS) use the Team Explorer add-in in Excel?
HTTP code 407: Proxy Authentication Required
When you see this error, most of the time, it’s caused by the fact that your organization is using a proxy. The proxy credentials are not properly passed through the Excel add-in and you end up with the error above.
I had the same problem when connecting to TFS from Visual Studio. There I solved it by updating the devenv.exe.config with the following section:
But Excel doesn’t have a config file, so I was thinking I couldn’t use the same solution. I was wrong, what you can do is create a new Excel.exe.config file, put the same information in as above and place it on the same location as Excel.exe.
This solved the problem for me…