Hey, I'm getting the error named in the title. There are no more infos available in the console. After it fails to initialize die Oculus VR, it tries to enable OpenVR, but fails because of "XR: OpenVR Error! ... error code VRInitError_Init_HmdNotFound". I've already tried to:
Reinstall the Oculus Plugin
Create a new project (it doesn't even run with an empty world, only with a light source)
Update Unity (didn't work with versions 2019.2.17f1 AND 2019.3.3f1)
Reinstall SteamVR (for whatever reasons it always start SteamVR when pressing "Play" in Unity)
I found the solution: For whatever reason, I have to run Unity on an Administrator Account for Oculus to work, it's not enough to select another (administrator) user when selecting "Run as Administrator"...