vllm-project/vllm · error · ValueError

No compilation mode is set.

Error message

No compilation mode is set.

What it means

Error "No compilation mode is set." thrown in vllm-project/vllm.

Source

Thrown at vllm/config/compilation.py:1086

    ) -> str | Callable:
        """
        Initialize the backend for the compilation config from a vllm config.
        Arguments:
            vllm_config: The vllm config to initialize the backend from.
            prefix: Cache directory prefix for this compiled module.
            is_encoder: Whether this module is used in an encoder (as
                opposed to a text backbone).
        Returns:
            The backend for the compilation config.
        """
        if self.mode is None:
            raise ValueError(
                "No compilation mode is set. This method should only be "
                "called via vllm config where the level is set if none is "
                "provided."
            )
        if self.mode == CompilationMode.NONE:
            raise ValueError("No compilation mode is set.")

        from torch._dynamo.backends.registry import list_backends

        torch_backends = list_backends(exclude_tags=tuple())
        if self.mode in [
            CompilationMode.STOCK_TORCH_COMPILE,
            CompilationMode.DYNAMO_TRACE_ONCE,
        ]:
            if self.backend in torch_backends:
                return self.backend
            return resolve_obj_by_qualname(self.backend)

        assert self.mode == CompilationMode.VLLM_COMPILE
        if self.backend not in ["eager", "inductor"]:
            logger.info("Using OOT custom backend for compilation.")

        from vllm.compilation.backends import VllmBackend

View on GitHub (pinned to c794754062)

Solutions

1. Set a compilation mode (e.g. -O0 through -O3 or --compilation-config level=N) before calling this method.

When it happens

Trigger: Raised at vllm/config/compilation.py:1086 when validation fails: No compilation mode is set.. Typically triggered by an incompatible or incomplete vLLM configuration, an unsupported platform/backend combination, or a runtime resource/dependency that is missing.

Common situations: Commonly encountered at vllm/config/compilation.py:1086 during vLLM startup/config validation or runtime setup when: (1) conflicting CLI flags or config fields are combined, (2) the current platform (CUDA/ROCm/CPU/XPU) or installed optional packages do not support the requested feature, or (3) a required value is absent or out of range. Resolve by correcting the configuration as described in the message, or by selecting a supported alternative.

AI-assisted analysis of vllm-project/vllm@c794754062 (2026-08-14). Data as JSON: /api/errors/adc3e8650e5996df. Report an issue: GitHub.