An error occurred while attempting to train

[124518]

ValueError: Caught ValueError in DataLoader worker process 3.
Original Traceback (most recent call last):
File "/home/ubuntu/users/liangyinghao/miniconda3/envs/mvp/lib/python3.7/site-packages/torch/utils/data/_utils/worker.py", line 185, in _worker_loop
data = fetcher.fetch(index)
File "/home/ubuntu/users/liangyinghao/miniconda3/envs/mvp/lib/python3.7/site-packages/torch/utils/data/_utils/fetch.py", line 44, in fetch
data = [self.dataset[idx] for idx in possibly_batched_index]
File "/home/ubuntu/users/liangyinghao/miniconda3/envs/mvp/lib/python3.7/site-packages/torch/utils/data/_utils/fetch.py", line 44, in
data = [self.dataset[idx] for idx in possibly_batched_index]
File "/mnt/DataDrive52/lyh/mvp/run/../lib/dataset/shelf.py", line 240, in getitem
m,i = super().getitem(self.num_views * idx + k)
ValueError: too many values to unpack (expected 2)
I have checked the source code and found that there are two return values, but this error keeps occurring. Can you please help me solve it?