I was struggling to feed my predictions into an sklearn function
M_ = M.data.numpy()

I got error
RuntimeError: numpy conversion for LongTensor is not supported

I tried some other things. Didn’t work and I gave up.
Then I start reading the docs. I found out it should be
M_ = M.data.cpu().numpy()

I suggest to improve this error message. Maybe something like
RuntimeError: numpy conversion for LongTensor is not supported on CUDA

That way, novices like me will know what to do