pytorch / pytorch/vision

SSL verification error while downloading MNIST dataset

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#9,183 1 comment 1 reaction 1 assignee View on GitHub

@AntoineSimoulin is already working on this.

Since Aug 29, 2025.

bug
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Description

🐛 Describe the bug
import torch
from torch.utils.data import DataLoader
import torchvision
from torchvision import transforms, datasets
import ssl
ssl._create_default_https_context = ssl._create_unverified_context



transform = transforms.Compose([
    transforms.Resize((64,64)),
    transforms.ToTensor(),
    transforms.Normalize((0.5,), (0.5,))
])

train_dataset = torchvision.datasets.MNIST(
    root='../../datasets',
    train=True,
    download=True,
    transform=transform
)
RuntimeError                              Traceback (most recent call last)
Cell In[32], [line 16](vscode-notebook-cell:?execution_count=32&line=16)
      6 ssl._create_default_https_context = ssl._create_unverified_context
     10 transform = transforms.Compose([
     11     transforms.Resize((64,64)),
     12     transforms.ToTensor(),
     13     transforms.Normalize((0.5,), (0.5,))
     14 ])
---> [16](vscode-notebook-cell:?execution_count=32&line=16) train_dataset = torchvision.datasets.MNIST(
     17     root='../../datasets',
     18     train=True,
     19     download=True,
     20     transform=transform
     21 )

File ~/Projects/PMLSolutions/.venv/lib/python3.13/site-packages/torchvision/datasets/mnist.py:100, in MNIST.__init__(self, root, train, transform, target_transform, download)
     97     return
     99 if download:
--> [100](https://file+.vscode-resource.vscode-cdn.net/Users/sujitwarrier/Projects/PMLSolutions/src/PMLSolutions/~/Projects/PMLSolutions/.venv/lib/python3.13/site-packages/torchvision/datasets/mnist.py:100)     self.download()
    102 if not self._check_exists():
    103     raise RuntimeError("Dataset not found. You can use download=True to download it")

File ~/Projects/PMLSolutions/.venv/lib/python3.13/site-packages/torchvision/datasets/mnist.py:197, in MNIST.download(self)
    195 for mirror, err in zip(self.mirrors, errors):
...
Tried https://ossci-datasets.s3.amazonaws.com/mnist/, got:
<urlopen error [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: unable to get local issuer certificate (_ssl.c:1028)>
Tried http://yann.lecun.com/exdb/mnist/, got:
HTTP Error 404: Not Found
Versions

torchvision=0.22.1
torch=2.7.1

The SSL errors are even occuring with the newer ossci links as shown.

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