sgl-project/sglang · error · AttributeError

module {__name__!r} has no attribute {name!r}

Error message

module {__name__!r} has no attribute {name!r}

What it means

The diffusion package uses PEP 562 lazy imports: its __getattr__ resolves public names listed in _EXPORTS to their defining submodule on first access. If the requested attribute is not in _EXPORTS at all, it raises a plain AttributeError (module has no attribute), which for `from ... import x` surfaces as ImportError.

Source

Thrown at python/sglang/kernels/ops/diffusion/__init__.py:495

    "unmount_lingbot_video_rmsnorm": "sites.lingbot_video_rmsnorm_site",
    "mark_sana_video_linear_attention_site": "sites.sana_video_linear_attention_site",
    "mount_sana_video_linear_attention": "sites.sana_video_linear_attention_site",
    "sana_video_linear_attention_active": "sites.sana_video_linear_attention_site",
    "try_sana_video_linear_attention": "sites.sana_video_linear_attention_site",
    "unmount_sana_video_linear_attention": "sites.sana_video_linear_attention_site",
    "QualityGatedFusion": "sites.quality_gate",
    # JIT C++/CUDA extensions (not kernels, not in the registry)
    "interpolate": "ext.hunyuan3d_rasterizer",
    "rasterize": "ext.hunyuan3d_rasterizer",
    "meshVerticeInpaint": "ext.mesh_processor",
}


def __getattr__(name: str) -> Any:
    """Resolve a public symbol to its submodule on first access (PEP 562)."""
    module = _EXPORTS.get(name)
    if module is None:
        raise AttributeError(f"module {__name__!r} has no attribute {name!r}")
    from importlib import import_module

    value = getattr(import_module(f"{__name__}.{module}"), name)
    globals()[name] = value  # cache; later lookups skip __getattr__ entirely
    return value


def __dir__() -> list[str]:
    return sorted(set(globals()) | set(_EXPORTS))


__all__ = sorted(_EXPORTS)

View on GitHub (pinned to 0132848349)

Solutions

1. Check the package's _EXPORTS mapping (or its __all__) for the exact public name
2. Update sglang if the symbol was renamed — consult the module's changelog
3. Import the internal helper from its concrete submodule path if you truly need it

Example fix

# before
from sglang.kernels.ops.diffusion import fused_bias_sliu  # typo
# after
from sglang.kernels.ops.diffusion import fused_bias_silu

from sglang.kernels.ops import diffusion
assert hasattr(diffusion, name), f'{name} not exported; check diffusion._EXPORTS'

def diffusion_exports(name: str) -> bool:
    from sglang.kernels.ops.diffusion import _EXPORTS
    return name in _EXPORTS

When it happens

Trigger: Accessing sglang.kernels.ops.diffusion.<name> where <name> is a typo (e.g. `fused_bias_sliu`) or a private/internal symbol never registered in _EXPORTS.

Common situations: IDE autocompletion guessing wrong names, using a symbol renamed between sglang versions, or trying to reach a helper function that was never exported.

Related errors

• module {__name__!r} has no attribute {name!r}
• Unsupported content type ${header.content_type}
• module {__name__!r} has no attribute {name!r}
• unsupported input for Sana fused bias-SiLU
• unsupported input for Sana fused bias-GLU

AI-assisted analysis of sgl-project/sglang@0132848349 (2026-08-28). Data as JSON: /api/errors/b6f92e12e4462be9. Report an issue: GitHub.