vllm-project/vllm · error · ValueError

CUDAGraphMode.{cudagraph_mode.name} is not supported with {m

Error message

CUDAGraphMode.{cudagraph_mode.name} is not supported with {min_cg_attn_backend} backend (support: {min_cg_support}); please try cudagraph_mode=PIECEWISE, and make sure compilation mode is VLLM_COMPILE

What it means

Error "CUDAGraphMode.{cudagraph_mode.name} is not supported with {min_cg_attn_backend} backend (support: {min_cg_support}); please try cudagraph_mode=PIECEWISE, and make sure compilation mode is VLLM_COMPILE" thrown in vllm-project/vllm.

Source

Thrown at vllm/config/compilation.py:1403

            return CUDAGraphMode.NONE

        # Check cudagraph for mixed batch is supported
        if (
            cudagraph_mode.mixed_mode() == CUDAGraphMode.FULL
            and min_cg_support != AttentionCGSupport.ALWAYS
        ):
            msg = (
                f"CUDAGraphMode.{cudagraph_mode.name} is not supported "
                f"with {min_cg_attn_backend} backend (support: "
                f"{min_cg_support})"
            )
            if min_cg_support == AttentionCGSupport.NEVER:
                # if not supported any full cudagraphs, just raise it.
                msg += (
                    "; please try cudagraph_mode=PIECEWISE, and "
                    "make sure compilation mode is VLLM_COMPILE"
                )
                raise ValueError(msg)

            # attempt to resolve the full cudagraph related mode
            if self.splitting_ops_contain_attention():
                msg += "; setting cudagraph_mode=FULL_AND_PIECEWISE"
                cudagraph_mode = CUDAGraphMode.FULL_AND_PIECEWISE
            else:
                msg += "; setting cudagraph_mode=FULL_DECODE_ONLY"
                cudagraph_mode = CUDAGraphMode.FULL_DECODE_ONLY
            logger.warning(msg)

        # check that if we are doing decode full-cudagraphs it is supported
        if (
            cudagraph_mode.decode_mode() == CUDAGraphMode.FULL
            and min_cg_support == AttentionCGSupport.NEVER
        ):
            msg = (
                f"CUDAGraphMode.{cudagraph_mode.name} is not supported "
                f"with {min_cg_attn_backend} backend (support: "

View on GitHub (pinned to c794754062)

Solutions

1. Set cudagraph_mode=PIECEWISE in the compilation config.
2. Ensure compilation mode is VLLM_COMPILE (-O3).
3. Or select an attention backend with stronger CUDA graph support.

When it happens

Trigger: Raised at vllm/config/compilation.py:1403 when validation fails: CUDAGraphMode not supported with the selected attention backend; try cudagraph_mode=PIECEWISE with compilation mode VLLM_COMPILE. 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:1403 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/991e587cf89f365f. Report an issue: GitHub.