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FAQ

Common Errors

Error Solution
OSError: You are trying to access a gated repo See Failing pytest tests due to Hugging Face errors below.
OSError: Too many open files when training with S3-hosted data Run ulimit -n 65535 (or at least 4096) before launching training.
raise ReadError("empty file") from None during training The number of workers is too high. Reduce --data.num_workers.
Unable to locate AWS credentials Configure AWS credentials via aws configure or any method documented in the AWS CLI configuration guide. Verify with aws sts get-caller-identity.

Failing pytest tests due to Hugging Face errors

This error usually appears as:

FAILED tests/essential/data/test_robotics_dataloader.py::test_batch_size[2]
    - OSError: You are trying to access a gated repo.

The tests use public HuggingFace models (e.g., SmolVLM2-256M) that do not require gated access. However, you still need an HF token for authenticated downloads.

1. HF token

Create a Hugging Face token at https://huggingface.co/settings/tokens. The token permissions need to be set to Write.

Then make the token available locally using either method:

  • Place it in ~/.cache/huggingface/token
  • Add export HF_TOKEN=hf-your-token-here to your ~/.bashrc

2. HF token on GitHub

When running tests from your own fork, you need to add your HF_TOKEN as a GitHub repository secret. In your fork, go to Settings > Secrets and variables > Actions and create a secret called HF_TOKEN.

HF Token Settings