sgl-project/sglang · error · ValueError

{} did not declare component use: {}

Error message

{} did not declare component use: {}

What it means

Stages must declare component usage (e.g. transformer/text-encoder use sites) up front via declared component-use records; _declared_component_use looks up a declared use by component_name (+optional phase, target_dtype) and raises if none matches.

Source

Thrown at python/sglang/multimodal_gen/runtime/pipelines_core/stages/base.py:217

    def _declared_component_use(
        self,
        *,
        component_name: str,
        phase: str | None = None,
        target_dtype: torch.dtype | None = None,
    ) -> ComponentUse:
        manager = self._component_residency_manager
        stage_name = self._active_component_stage_name()
        server_args = manager.server_args if manager is not None else self.server_args
        for use in self.component_uses(server_args, stage_name):
            if use.component_name != component_name:
                continue
            if phase is not None and use.phase != phase:
                continue
            if target_dtype is not None:
                return replace(use, target_dtype=target_dtype)
            return use
        raise ValueError(
            f"{self.__class__.__name__} did not declare component use: "
            f"{component_name}"
        )

    @contextmanager
    def use_declared_component(
        self,
        *,
        component_name: str,
        module=None,
        phase: str | None = None,
        target_dtype: torch.dtype | None = None,
    ) -> Iterator[object | None]:
        """reference a component already declared in `component_uses`"""
        use = self._declared_component_use(
            component_name=component_name,
            phase=phase,
            target_dtype=target_dtype,

View on GitHub (pinned to 0132848349)

Solutions

1. Declare the component use in the stage (add to its declared component-use list/property) with the same name and phase
2. Fix the component_name string/typo to match the declaration
3. Check phase and target_dtype arguments match a declared entry

uses = stage.declared_component_uses() if hasattr(stage, 'declared_component_uses') else []
names = {u.component_name for u in uses}
assert 'transformer' in names

When it happens

Trigger: Calling stage.use_declared_component('transformer') (or begin_declared_component_use / internal transform use-site helpers) when the stage class never declared that component, or declared it under a different phase.

Common situations: Subclassing a Stage and overriding declarations; renaming a component or phase constant between versions; calling the context manager with a typo in the component name.

Related errors

• pipeline_cls must inherit from ComposedPipelineBase
• Pipeline '{pipeline_name}' is already registered; pass overw
• Grouped pipeline returned fewer outputs than requests.
• Expected {len(reqs)} grouped outputs, got {len(output_batch.
• Unknown image_vae_encoding_position: {image_vae_encoding_pos

AI-assisted analysis of sgl-project/sglang@0132848349 (2026-08-28). Data as JSON: /api/errors/7a0d9323facbaa34. Report an issue: GitHub.