We have an old server machine with TFS 2012 installed on it. It has the \'DefaultCollection\' of project collection. We want to copy (not move, i.e. leaving the collection i
It depends a bit on how complicated your TFS installation is, but here are the steps for a simpler one server setup without Sharepoint:
The above is a shorter version of this: https://msdn.microsoft.com/en-us/library/dd936158(v=vs.110).aspx
Edit: I have successfully used the above approach to make a test migration from TFS 2010 to TFS 2013 RTM followed by the migration of our production environment. We use the server with the test migration for testing new updates before applying to production and we have done so with all updates from 2013 RTM until 2015 Update 3. I am currently applying the same approach in upgrading to 2017 in order to get a fresh server with never version of SQL.