title: pytorch torchvision.datasets.ImageFolder FileNotFoundError: Found no valid file for the classes .ipynb_checkpoints
body: <p>Tried to load training data with pytorch torch.datasets.ImageFolder in Colab.</p>
  <pre><code>transform = transforms.Compose([transforms.Resize(400),
                                  transforms.ToTensor()])
  dataset_path = 'ss/'
  dataset = datasets.ImageFolder(root=dataset_path, transform=transform)
  dataloader = torch.utils.data.DataLoader(dataset, batch_size=20)
  </code></pre>
  <p>I encountered the following error :</p>
  <pre><code>---------------------------------------------------------------------------
  FileNotFoundError                         Traceback (most recent call last)
  &lt;ipython-input-27-7abcc1f434b1&gt; in &lt;module&gt;()
        2                                 transforms.ToTensor()])
        3 dataset_path = 'ss/'
  ----&gt; 4 dataset = datasets.ImageFolder(root=dataset_path, transform=transform)
        5 dataloader = torch.utils.data.DataLoader(dataset, batch_size=20)
  
  3 frames
  /usr/local/lib/python3.7/dist-packages/torchvision/datasets/folder.py in make_dataset(directory, class_to_idx, extensions, is_valid_file)
      100         if extensions is not None:
      101             msg += f&quot;Supported extensions are: {', '.join(extensions)}&quot;
  --&gt; 102         raise FileNotFoundError(msg)
      103 
      104     return instances
  
  FileNotFoundError: Found no valid file for the classes .ipynb_checkpoints. Supported extensions are: .jpg, .jpeg, .png, .ppm, .bmp, .pgm, .tif, .tiff, .webp
  </code></pre>
  <p>My Dataset folder contains a subfolder with many training images in png format, still the ImageFolder can't access them.</p>