Error in data loader

I created my own torch geometric graph classification dataset. However, I encounter the following problem:

Traceback (most recent call last):
  File "/snap/pycharm-community/240/plugins/python-ce/helpers/pydev/pydevd.py", line 1483, in _exec
    pydev_imports.execfile(file, globals, locals)  # execute the script
  File "/snap/pycharm-community/240/plugins/python-ce/helpers/pydev/_pydev_imps/_pydev_execfile.py", line 18, in execfile
    exec(compile(contents+"\n", file, 'exec'), glob, loc)
  File "/home/eitank/GraphVid/train_kinetics.py", line 207, in <module>
    args=args
  File "/home/eitank/GraphVid/train_kinetics.py", line 119, in train_video_recognition
    batch_splitter=classification_batch_splitter,
  File "/home/eitank/GraphVid/utils/PackageUtils/TorchUtils.py", line 168, in fit
    batch_splitter=batch_splitter, )
  File "/home/eitank/GraphVid/utils/PackageUtils/TorchUtils.py", line 263, in do_epoch
    for iteration, batch in enumerate(data_iter):
  File "/home/eitank/anaconda3/envs/torch/lib/python3.7/site-packages/torch/utils/data/dataloader.py", line 435, in __next__
    data = self._next_data()
  File "/home/eitank/anaconda3/envs/torch/lib/python3.7/site-packages/torch/utils/data/dataloader.py", line 475, in _next_data
    data = self._dataset_fetcher.fetch(index)  # may raise StopIteration
  File "/home/eitank/anaconda3/envs/torch/lib/python3.7/site-packages/torch/utils/data/_utils/fetch.py", line 47, in fetch
    return self.collate_fn(data)
  File "/home/eitank/anaconda3/envs/torch/lib/python3.7/site-packages/torch_geometric/data/dataloader.py", line 36, in __call__
    return self.collate(batch)
  File "/home/eitank/anaconda3/envs/torch/lib/python3.7/site-packages/torch_geometric/data/dataloader.py", line 31, in collate
    return [self.collate(s) for s in zip(*batch)]
  File "/home/eitank/anaconda3/envs/torch/lib/python3.7/site-packages/torch_geometric/data/dataloader.py", line 31, in <listcomp>
    return [self.collate(s) for s in zip(*batch)]
  File "/home/eitank/anaconda3/envs/torch/lib/python3.7/site-packages/torch_geometric/data/dataloader.py", line 17, in collate
    self.exclude_keys)
  File "/home/eitank/anaconda3/envs/torch/lib/python3.7/site-packages/torch_geometric/data/batch.py", line 151, in from_data_list
    batch[key] = torch.cat(items, cat_dim)
TypeError: expected Tensor as element 40 in argument 0, but got NoneType

How can I find the cause? I checked if the value returned with my dataset is None, and it isn’t.

Did you check the entire items content, as it seems that “element 40” is causing the issue and is a None?