TFS 2015:No agent could be found with the following capabilities: msbuild, visualstudio, vstest

Question

We have recently upgraded to TFS 2015 Update 4. When I tried to do a build, I am getting the following error:

There are issues with the request or def

Answer 1

I was getting the same error out of the blue and it was running fine the previous week. Restarting the build agent service resolved the error for me