Error whilst trying to run ava demo

Traceback (most recent call last):
File "tools/run_net.py", line 51, in
main()
File "tools/run_net.py", line 47, in main
demo(cfg)
File "/home/SlowFast-master/tools/demo_net.py", line 114, in demo
for task in tqdm.tqdm(run_demo(cfg, frame_provider)):
File "/home/venv/lib/python3.6/site-packages/tqdm/std.py", line 1167, in __iter__
for obj in iterable:
File "/home/SlowFast-master/tools/demo_net.py", line 59, in run_demo
model = ActionPredictor(cfg=cfg, async_vis=async_vis)
File "/home/SlowFast-master/slowfast/visualization/predictor.py", line 132, in __init__
self.predictor = Predictor(cfg=cfg, gpu_id=gpu_id)
File "/home/SlowFast-master/slowfast/visualization/predictor.py", line 46, in __init__
cu.load_test_checkpoint(cfg, self.model)
File "/home/SlowFast-master/slowfast/utils/checkpoint.py", line 468, in load_test_checkpoint
load_checkpoint(last_checkpoint, model, cfg.NUM_GPUS > 1)
File "/home/SlowFast-master/slowfast/utils/checkpoint.py", line 285, in load_checkpoint
checkpoint = torch.load(f, map_location="cpu")
File "/home/venv/lib/python3.6/site-packages/torch/serialization.py", line 587, in load
with _open_zipfile_reader(opened_file) as opened_zipfile:
File "/home/venv/lib/python3.6/site-packages/torch/serialization.py", line 242, in __init__
super(_open_zipfile_reader, self).__init__(torch._C.PyTorchFileReader(name_or_buffer))
RuntimeError: [enforce fail at inline_container.cc:145] . PytorchStreamReader failed reading zip archive: failed finding central directory