[horstepipe]

Hey guys,
just got an Apple TV 4K and tried to install the current Kodi build. I did it quite often before for friends on Apple TV 4s with a paid developer account.
Unfortunately now I'm getting:
"App installation failed. There was an internal API error"

Looks like there are quite a lot of people with that problem since the past months, has something changed here?
I'm using VMVare on Windows to run Xcode, successfully paired my AppleTV 4K with xcode and signed the ipa with the IOS App Signer.

MacOS v10.12.6
xCode v9.2

I'm a little scared that Apple starts blocking sideloading Kodi now, hope somebody can settle me down

They do not block side loading. Apple does not care even slightly about side loading because if they did they would block the process which would be extremely simple to do.

You are missing a step. Does your developer account have the device added? Does the provisioning profile have the device added to it? Did you also add that provisioning profile to the device after it was created?

I am willing to bet one of those was missed.  

have these processes been changed? With Apple TV 4, I connected it via USB, xcode recognized it and everything was fine

edit: sorry, you were right :-)
I didn't select the Apple TV in the main window of xcode...
shame on me