Recently I started receiving the following error when trying to edit TFS 2010 build templates on my machine: Type ‘IBuildDetail’ is not defined This was exceptionally weird as TFS was running happily for quite a while. Turns out the culprit was the Developer Preview edition of Visual Studio 11 that I installed alongside the existing VS2010. Anyway, in order to solve the problem: 1. Open your build template (the .xaml file) in code mode. (From the Source Explorer, right-click the file, choose ‘View...