I’m seeing same problem. Running windows, python 3.7.7, latest pytorch version. Issue seen only with num_workers>0. I tried modifying Anaconda3\envs\test\Lib\multiprocessing\reduction.py with def dump(obj, file, protocol=4, but it didn’t help. Is there a different way to force protocol version or any other workaround. I’m running the code in https://github.com/seungwonpark/melgan.git 43.