huggingface/transformers · error · ValueError

An error occurred while trying to load from '{repo_id}': {e}

Error message

An error occurred while trying to load from '{repo_id}': {e}.

What it means

After a hub kernel repo id is parsed, transformers calls `get_kernel(repo_id, revision, version, allow_all_kernels)` and wraps any non-ValueError failure into a ValueError with the repo id and the underlying exception text. This is a boundary error: the real cause (network failure, missing repo, auth, bad revision, unsigned kernel with allow_all_kernels=False) is in `{e}`.

Source

Thrown at src/transformers/integrations/hub_kernels.py:647

    # extract the rev after the @ if it exists
    repo_id, _, rev = repo_id.partition("@")
    repo_id = repo_id.strip()

    # create revision xor version
    rev = rev.strip() if rev else None
    version = None
    if rev is None:
        # FA4 is still in beta -> redirect to v0 else default to v1
        is_fa4 = is_flash_attention_requested(requested_attention_implementation=repo_id, version=4)
        version = 0 if is_fa4 else 1

    # Load the kernel from hub
    try:
        kernel = get_kernel(repo_id, revision=rev, version=version, allow_all_kernels=allow_all_kernels)
    except ValueError:
        raise
    except Exception as e:
        raise ValueError(f"An error occurred while trying to load from '{repo_id}': {e}.")

    # correctly wrap the kernel
    mask_implementation = "flash_attention_2"
    if hasattr(kernel, "flash_attn_varlen_func"):
        if attention_wrapper is None:
            attention_wrapper = flash_attention_forward
        kernel_function = attention_wrapper
    elif hasattr(kernel, "sparse_atten_func"):
        # Block-sparse kernels (e.g. `kernels-staging/msa`) expose `sparse_atten_func` instead of
        # `flash_attn_varlen_func`; their call contract differs from the attention interface, so we
        # bind the dedicated transformers-side wrapper that adapts the arguments and hides the
        # prefill-kernel / decode-fallback dispatch.
        from .msa_attention import msa_attention_forward

        kernel_function = attention_wrapper if attention_wrapper is not None else msa_attention_forward
        mask_implementation = "sdpa"
    elif kernel_name is not None:
        kernel_function = getattr(kernel, kernel_name)

View on GitHub (pinned to a597f97485)

Solutions

  1. Read the embedded `{e}` text first — it names the actual transport/repo failure.
  2. Verify the repo exists and the id/revision are exact: open `https://huggingface.co/<repo_id>` and check tags/commits for `@rev`.
  3. For kernels outside `kernels-community`, pass `allow_all_kernels=True` (only for sources you trust).
  4. Check network/credentials (`huggingface-cli login`, HF_ENDPOINT reachability) if `{e}` mentions connection or 401/403 errors.

Example fix

# before
model = AutoModelForCausalLM.from_pretrained(m, attn_implementation="kernels-community/flash-attn3@badrev")
# ValueError: An error occurred while trying to load from 'kernels-community/flash-attn3': ...

# after
model = AutoModelForCausalLM.from_pretrained(
    m,
    attn_implementation="kernels-community/flash-attn3",  # valid repo/revision
    allow_all_kernels=True,  # only for trusted non-community kernels
)
Defensive patterns

Strategy: retry

Validate before calling

from huggingface_hub import HfApi
api = HfApi()
assert api.repo_exists(repo_id), f"kernel repo {repo_id} does not exist"
if rev:
    assert any(r == rev for r in [c.commit_id for c in api.list_repo_commits(repo_id)]) or rev in api.list_repo_refs(repo_id).convert(), "bad revision"

Try / catch

import time
for attempt in range(3):
    try:
        model = load_with_kernel_attn(repo_id)
        break
    except ValueError as e:
        msg = str(e)
        if "An error occurred while trying to load" not in msg:
            raise
        inner = msg.split(":", 1)[1]
        if any(s in inner for s in ("Connection", "timed out", "401", "403", "404")) and attempt < 2:
            time.sleep(2 ** attempt)
            continue
        raise

Prevention

When it happens

Trigger: Requesting `attn_implementation="kernels-community/flash-attn"` (or a custom `user/repo@rev`) where the repo does not exist, the revision is invalid, the Hub is unreachable, or the kernel is outside `kernels-community` and `allow_all_kernels` was not enabled — any of these makes `get_kernel_hub` raise, which is then re-wrapped here.

Common situations: Typos in repo ids; offline or firewalled environments; private/unverified kernel repos requiring `trust_remote_code`/`allow_all_kernels=True`; pinned revisions that were deleted.

Related errors

AI-assisted analysis of huggingface/transformers@a597f97485 (2026-08-14). Data as JSON: /api/errors/c318ac4eba0940fe. Report an issue: GitHub.