Cycles never loads render kernels with motion blur

For some reason if I turn on motion blur, cycles gets stuck loading render kernels forever. If I turn it off, it only takes about half a second to load. I checked task manager and my cpu, gpu, ram and vram are not doing anything. It’s like they’re just idle and blender isn’t doing anything at all. Has anyone else had this happen before or have any ideas I could try?

I’m using version 2.93 with a 10th gen i7 and an rtx 2060.

Maybe the optix cache is broken. To fix this you have to:
C:\Users\YOURUSERNAME\AppData\Local\NVIDIA\OptixCache

and delete or rename the file:
cache7.db

Optix will automatically create it again when you render the next time.

I have also had similar problems when my C: drive was full.

I’ll give that a shot. I had to delete it when I first download 2.93 because I guess the cash was made by 2.92 and wasn’t compatible or something.

Fixed it. I’m an idiot. I just waited a really long time. I guess I’ve never used motion blur since I deleted the optix cash so it had to re-load a bunch of stuff. Still weird that it froze for several minutes and didn’t use the cpu, gpu or memory.

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Motion blur causes kernel reload? Interesting. Didnt know that.

I have the exact same problem: Blender 2.93.5 gets stuck initializing when using motion blur. No problem without motion blur. I don’t use Optix with my “old” NVidia 1060. But nevertheless I deleted the files under the cache directory as described above. No change! Any other tips what’s going on here?

PS: Despite doing apparently nothing Blender burns around 12% CPU power according to the windows task manager.