Latest photon Controller (4.x) want's to install .NET 3.5?

Hey there,

I have just setup my first photon server on my dedicated window 2016 server machine - and everything works fine - send my first chat message via a quick and dirty empty project from android handy (unity) to server - awesome!
However once I start the Photon Controller (from deploy/win64) it always asks me to install .NET 3.5? From what I read photon 4.x should only require .NET 4.0+ ?

So while the application itself seems to run fine, I always get this annoying "something tries to install .NET 3.5 feature" upon loading of the controller app. Any ideas, what is causing this?

Thanks,
Oliver