Siamese Network Tutorial AttributeError: module 'torch._C' has no attribute 'DisableTorchFunction'

When I arrive to learn.lr_find()

I got this

---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-139-d81c6bd29d71> in <module>
----> 1 learn.lr_find()

~/anaconda3/envs/pytorch3d/lib/python3.8/site-packages/fastai/callback/schedule.py in lr_find(self, start_lr, end_lr, num_it, stop_div, show_plot, suggestions)
    226     n_epoch = num_it//len(self.dls.train) + 1
    227     cb=LRFinder(start_lr=start_lr, end_lr=end_lr, num_it=num_it, stop_div=stop_div)
--> 228     with self.no_logging(): self.fit(n_epoch, cbs=cb)
    229     if show_plot: self.recorder.plot_lr_find()
    230     if suggestions:

~/anaconda3/envs/pytorch3d/lib/python3.8/site-packages/fastcore/logargs.py in _f(*args, **kwargs)
     54         init_args.update(log)
     55         setattr(inst, 'init_args', init_args)
---> 56         return inst if to_return else f(*args, **kwargs)
     57     return _f

~/anaconda3/envs/pytorch3d/lib/python3.8/site-packages/fastai/learner.py in fit(self, n_epoch, lr, wd, cbs, reset_opt)
    205             self.opt.set_hypers(lr=self.lr if lr is None else lr)
    206             self.n_epoch = n_epoch
--> 207             self._with_events(self._do_fit, 'fit', CancelFitException, self._end_cleanup)
    208 
    209     def _end_cleanup(self): self.dl,self.xb,self.yb,self.pred,self.loss = None,(None,),(None,),None,None

~/anaconda3/envs/pytorch3d/lib/python3.8/site-packages/fastai/learner.py in _with_events(self, f, event_type, ex, final)
    153 
    154     def _with_events(self, f, event_type, ex, final=noop):
--> 155         try:       self(f'before_{event_type}')       ;f()
    156         except ex: self(f'after_cancel_{event_type}')
    157         finally:   self(f'after_{event_type}')        ;final()

~/anaconda3/envs/pytorch3d/lib/python3.8/site-packages/fastai/learner.py in _do_fit(self)
    195         for epoch in range(self.n_epoch):
    196             self.epoch=epoch
--> 197             self._with_events(self._do_epoch, 'epoch', CancelEpochException)
    198 
    199     @log_args(but='cbs')

~/anaconda3/envs/pytorch3d/lib/python3.8/site-packages/fastai/learner.py in _with_events(self, f, event_type, ex, final)
    153 
    154     def _with_events(self, f, event_type, ex, final=noop):
--> 155         try:       self(f'before_{event_type}')       ;f()
    156         except ex: self(f'after_cancel_{event_type}')
    157         finally:   self(f'after_{event_type}')        ;final()

~/anaconda3/envs/pytorch3d/lib/python3.8/site-packages/fastai/learner.py in _do_epoch(self)
    189 
    190     def _do_epoch(self):
--> 191         self._do_epoch_train()
    192         self._do_epoch_validate()
    193 

~/anaconda3/envs/pytorch3d/lib/python3.8/site-packages/fastai/learner.py in _do_epoch_train(self)
    181     def _do_epoch_train(self):
    182         self.dl = self.dls.train
--> 183         self._with_events(self.all_batches, 'train', CancelTrainException)
    184 
    185     def _do_epoch_validate(self, ds_idx=1, dl=None):

~/anaconda3/envs/pytorch3d/lib/python3.8/site-packages/fastai/learner.py in _with_events(self, f, event_type, ex, final)
    153 
    154     def _with_events(self, f, event_type, ex, final=noop):
--> 155         try:       self(f'before_{event_type}')       ;f()
    156         except ex: self(f'after_cancel_{event_type}')
    157         finally:   self(f'after_{event_type}')        ;final()

~/anaconda3/envs/pytorch3d/lib/python3.8/site-packages/fastai/learner.py in all_batches(self)
    159     def all_batches(self):
    160         self.n_iter = len(self.dl)
--> 161         for o in enumerate(self.dl): self.one_batch(*o)
    162 
    163     def _do_one_batch(self):

~/anaconda3/envs/pytorch3d/lib/python3.8/site-packages/fastai/data/load.py in __iter__(self)
    100         self.before_iter()
    101         self.__idxs=self.get_idxs() # called in context of main process (not workers/subprocesses)
--> 102         for b in _loaders[self.fake_l.num_workers==0](self.fake_l):
    103             if self.device is not None: b = to_device(b, self.device)
    104             yield self.after_batch(b)

~/anaconda3/envs/pytorch3d/lib/python3.8/site-packages/torch/utils/data/dataloader.py in __next__(self)
    361 
    362     def __next__(self):
--> 363         data = self._next_data()
    364         self._num_yielded += 1
    365         if self._dataset_kind == _DatasetKind.Iterable and \

~/anaconda3/envs/pytorch3d/lib/python3.8/site-packages/torch/utils/data/dataloader.py in _next_data(self)
    987             else:
    988                 del self._task_info[idx]
--> 989                 return self._process_data(data)
    990 
    991     def _try_put_index(self):

~/anaconda3/envs/pytorch3d/lib/python3.8/site-packages/torch/utils/data/dataloader.py in _process_data(self, data)
   1012         self._try_put_index()
   1013         if isinstance(data, ExceptionWrapper):
-> 1014             data.reraise()
   1015         return data
   1016 

~/anaconda3/envs/pytorch3d/lib/python3.8/site-packages/torch/_utils.py in reraise(self)
    393             # (https://bugs.python.org/issue2651), so we work around it.
    394             msg = KeyErrorMessage(msg)
--> 395         raise self.exc_type(msg)

AttributeError: Caught AttributeError in DataLoader worker process 0.
Original Traceback (most recent call last):
  File "/home/alberto/anaconda3/envs/pytorch3d/lib/python3.8/site-packages/torch/utils/data/_utils/worker.py", line 185, in _worker_loop
    data = fetcher.fetch(index)
  File "/home/alberto/anaconda3/envs/pytorch3d/lib/python3.8/site-packages/torch/utils/data/_utils/fetch.py", line 34, in fetch
    data = next(self.dataset_iter)
  File "/home/alberto/anaconda3/envs/pytorch3d/lib/python3.8/site-packages/fastai/data/load.py", line 111, in create_batches
    yield from map(self.do_batch, self.chunkify(res))
  File "/home/alberto/anaconda3/envs/pytorch3d/lib/python3.8/site-packages/fastai/data/load.py", line 132, in do_batch
    def do_batch(self, b): return self.retain(self.create_batch(self.before_batch(b)), b)
  File "/home/alberto/anaconda3/envs/pytorch3d/lib/python3.8/site-packages/fastai/data/load.py", line 131, in create_batch
    def create_batch(self, b): return (fa_collate,fa_convert)[self.prebatched](b)
  File "/home/alberto/anaconda3/envs/pytorch3d/lib/python3.8/site-packages/fastai/data/load.py", line 48, in fa_collate
    else type(t[0])([fa_collate(s) for s in zip(*t)]) if isinstance(b, Sequence)
  File "/home/alberto/anaconda3/envs/pytorch3d/lib/python3.8/site-packages/fastai/data/load.py", line 48, in <listcomp>
    else type(t[0])([fa_collate(s) for s in zip(*t)]) if isinstance(b, Sequence)
  File "/home/alberto/anaconda3/envs/pytorch3d/lib/python3.8/site-packages/fastai/data/load.py", line 47, in fa_collate
    return (default_collate(t) if isinstance(b, _collate_types)
  File "/home/alberto/anaconda3/envs/pytorch3d/lib/python3.8/site-packages/torch/utils/data/_utils/collate.py", line 55, in default_collate
    return torch.stack(batch, 0, out=out)
  File "/home/alberto/anaconda3/envs/pytorch3d/lib/python3.8/site-packages/fastai/torch_core.py", line 317, in __torch_function__
    with torch._C.DisableTorchFunction(): ret = _convert(func(*args, **(kwargs or {})), self.__class__)
AttributeError: module 'torch._C' has no attribute 'DisableTorchFunction'

All the rest is working fine and displays images.

please can you show your data loader code