I have now installed Version 9.1.6119.0 (Aug 29, 2016) at least 20 times from scratch and when loading the project/solution in VS2015, I always receive the warning message about "Unresolved Project References for System.IO, System.Runtime and System.Threading.Tasks".
I have made no changes whatsoever in sitefinity yet. This is the first message I get and it will simply not go away.
Am I doing something wrong or have other users made the same experience ?
Weird, is it like you need to change your project to .net 4.5, or 4.5.1, or 4.6 or something?
I don't have this internal build setup, but I seem to remember them asking if we were cool with them making the default new framework one of those.