Compositor not available 400 error - related to GPU cache?
My Vive Pro had been displaying the Compositor not available (400) error for two days. I reseated the cables, power cycled link box, restarted SteamVR many times, updated my GPU driver, restarted my PC and reinstalled Steam/SteamVR but it persisted.
When I saw the 400 error before, reseating the cables and restarting the PC got rid of the error but this time I did everything I could think of and find from the internet and nothing helped. So I gave up and went to sleep.
Then the next day I just tried restarting SteamVR and it just started working again.
I checked the vrcompositor log and noticed that it kept saying "NvAPI: Failed to get direct display modes! Error='NVAPI_OK' NumModes=0 ... Failed to create direct mode display!" then all of a sudden it says "Creating nvapi display".
So I am wondering if the updated graphics card driver information wasn't getting through to SteamVR because of some GPU information cache and if so, where is this information stored so that I can jumpstart the process if this happens again?