Ok.  I’ll admit.  This error almost *never* comes up.  Nevertheless, I ran into it last week while I was doing a Team Foundation Server 2010 (TFS2010) upgrade and hardware migration for a customer.

It starts out with an error message when you try to connect to TFS that says “TF31001: Cannot connect to Team Foundation Server at server_name. The server returned the following error: Server was unable to process request. ---> Team Foundation services are not available from the server.”

When you go look at the Event Log on the TFS machine, you’ll find an error message that says something like “TF30046: The instance information does not match. Team Foundation expected 34fa79c8-a6d7-4eb7-a99a-91ca0e5a4105 but found 34a2a94f-8da8-40c0-b8e7-e03a1c3595df.”

The Solution: The simplest answer is to change the application id that TFS2010 is expecting.

Step 1: Go to the “C:Program FilesMicrosoft Team Foundation Server 2010Application TierWeb Services” folder on your TFS application tier machine

Step 2: Make a backup copy of the current web.config file

Step 3: Open Web.config in notepad

Step 4: Locate the appSettings applicationId key in web.config

Step 5: Replace the “value” with the “actual” guid from the event log error message

Step 6: Restart IIS

Step 7: Rejoice.

-Ben

-- Want some help setting up and using Team Foundation Server 2010?  Drop us a line at info@benday.com.