Recently, just after migrating to Visual Studio 2015 we have noticed, that our Continuous Integration Build, which is using TFS 2012 is not quite happy about our recent check-ins. A quick investigation lead us to conclusion that one of us by mistake used new feature of C# 6.0. As Visual Studio compiled solution without errors, developer thought that everything is OK, as there was no sign of sudden failure.

The first idea was – we need to upgrade our TFS Builds – but it was “no go” for us as it would mean that we need to migrate all our custom build activities as well. Hopefully for us – there was also another solution – much easier one.
All we had to do was:

1. Install Visual Studio 2o15 on Build machine
2. Edit build process template and point MSBuild activities to new location with MsBuild 14.0

… after this small change, everything was working again. All green! ;o)