After you upgrade Microsoft Visual Studio Team Foundation Server (TFS) config database to TFS 2012 Update 3 , you may encounter one of the following issues:
- You can't attach project collections that are detached from TFS 2010 or TFS 2012.
- You can reattach project collections that are detached from TFS 2012 or TFS 2012. However, your permissions or identities may be lost in TFS 2012.