Asp.Net Core 1.0 Error “Failed to make the following project runnable”

I faced the same problem, and thought that problem lied in project.fragment.lock.json or in project.json, but in my case the problem was with incorrect project.lock.json files. It seems like after addition of some new Nuget packages these files need to be recreated. When i deleted these files, packages have been restored correctly, and the solution successfully built. Hope it could help someone.