TFS 2017 - MSBuild 14 is default after VS 2017 15.5 update. Need MSBuild 15 back

Question

Our TFS 2017 Server / Build servers, we updated Visual Studio 2017 using the "Visual Studio Installer" to version app to the latest (15.5.27130) to support some of the features / fixes. When we did that update, TFS build processes now default to MSBuild 14.0, which does not have the C# features we use in MSBuild 15. I have tried updating TFS 2017 Update 3, as well as fully uninstalling VS 2017 and reinstalled. No different. All of our build services are failing now due to the wrong MS Build. This has been working with TFS 17, VS 17 for a year without issues.

I can see MSBuild 15 available in the path "C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\MSBuild\15.0\Bin"

My TFS Build Definitions also have "Latest" as well as when I select 2017 - but makes no difference.

I also see this in the output of the build which is concerning:

How come its not being detected? How can I change the default?

Note - I am not sure if this is the right place for StackOverflow, but it is development related with more people here that are familiar.

Answer 1

Ended up being simple... just have to update the build agent to the latest version. Reference: Visual Studio Developer Community problem report