Error running code

i keep getting this error, even though i have downgraded to torch 1.3.1

File “/home/dewe/anaconda3/envs/procgen/lib/python3.7/site-packages/ray/rllib/models/model.py”, line 198, in flatten
return torch.flatten(obs, start_dim=1)
TypeError: flatten(): argument ‘input’ (position 1) must be Tensor, not Tensor