Symptom: Cannot connect to TFS and the following error messages appear:

TF31002: Unable to connect to this Team Foundation Server: http://tfs.global.yourServer.name:8080/tfs.
Team Foundation Server Url: http://tfs.global.yourServer.name:8080/tfs.

Possible reasons for failure include:
– The name, port number, or protocol for the Team Foundation Server is incorrect.
– The Team Foundation Server is offline.
– The password has expired or is incorrect.

Technical information (for administrator):
The remote server returned an error: (503) Server Unavailable.

OR

TF30331: Team Explorer could not connect to the Team Foundation server http://tfs.global.yourServer.name:8080/tfs used during your last session. The server may be offline or the network is unavailable. Contact your Team Foundation Server administrator to confirm that the server is available on the network. Use the Connect to Team Foundation Server command on the Tools menu to reconnect to your previous server.

The server returned the following error: The request failed with HTTP status 503: Service Unavailable.

Cause and solution:

One thing that could cause these errors is the proxy setting on the client machine. Remember that the proxy setting that you set in IE will apply to the whole machine, and will affect other apps on that machine. As far as I know, some additional configurations are needed to get TFS to work with a proxy.

If you are getting the above errors, it is worthwile try turning off the proxy on your machine to see if that’d work and hence isolate the problem. To turn off proxy, go to IE, then Internet Options, then Connections tab, then LAN settings, then clear the “Use a proxy server checkbox“, also try clearing the “Automatically detect settings” checkbox.