One of the main reasons why client-issued web calls fail in TFS is that the system time-outs. It is important to note that, the time-out time is designed to prevent the UI from being locked out forever. Changing the time-out time by the method described in this post will increase the time-out time for every web call. So, it is generally a good idea to return the time-out time back to its default value after changing. (The default time is 10 min.)
It is possible to increase the time-out time by following the subsequent steps (all taken on the client machine):
1. Open the registry editor (go to start menu and in the run dialogue type regedit).
2. If you are on a 32-bit machine, then navigate to the key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\VisualStudio\9.0\TeamFoundation\RequestSettings. Alternatively, if you are on a 64-bit machine, then navigate to the key HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\VisualStudio\9.0\TeamFoundation\RequestSettings.
a. If TeamFoundation\RequestSettings does not exist, then right-click on the TeamFoundations key.
b. Chose to create a new key.
c. Name the key RequestSettings.
3. Change the value of DefaultTimeout to the new time-out time (the time is in milliseconds).
a. If DefaultTimeout does not exist, then right-click on the key RequestSettings.
b. Choose to create a new DWORD.
c. Once DefaultTimeout exists, right-click on it and choose modify, and enter the new time (in decimal).