extract_mesh.ipynb UnpicklingError :STACK_GLOBAL requires str

[epicgzs1112]

help! when i try to extract mesh lego ,it error! it stop at
if len(ckpts) > 0 and not args.no_reload:
ckpt_path = ckpts[-1]
print('Reloading from', ckpt_path)
ckpt = torch.load(ckpt_path)
i have update python to 3.8.2,but it's not work!