vllm-project/vllm · error · RuntimeError

NIXL transfer failed with state={state}

Error message

NIXL transfer failed with state={state}

What it means

Error "NIXL transfer failed with state={state}" thrown in vllm-project/vllm.

Source

Thrown at vllm/distributed/eplb/eplb_communicator.py:512

                if local_stride != peer_stride:
                    raise RuntimeError(
                        f"NIXL EPLB nbytes_per_expert mismatch for {key} "
                        f"with rank {peer}: "
                        f"local={local_stride}, peer={peer_stride}"
                    )
            self._remote_send_meta[peer] = peer_meta

    def _wait_for_all_transfers(self, handles: list[int]) -> None:
        pending = set(handles)
        while pending:
            completed: list[int] = []
            for handle in pending:
                state = self._nixl_wrapper.check_xfer_state(handle)
                if state == "DONE":
                    completed.append(handle)
                    continue
                if state != "PROC":
                    raise RuntimeError(f"NIXL transfer failed with state={state}")
            for handle in completed:
                pending.remove(handle)
            if pending:
                time.sleep(0.0005)

    def _create_peer_xfer(
        self,
        src: int,
        local_descs: list[tuple[int, int, int]],
        remote_descs: list[tuple[int, int, int]],
    ) -> tuple[int, int, int]:
        """Create a batched xfer for multiple descriptors from one peer.

        Each element in *local_descs* / *remote_descs* is an
        ``(address, size, device_id)`` tuple.

        Returns ``(local_dlist, remote_dlist, xfer_handle)``.
        """

View on GitHub (pinned to c794754062)

Solutions

1. Retry the operation or restart the workers; inspect NIXL logs for the transfer failure state reported in the error.

When it happens

Trigger: Raised at vllm/distributed/eplb/eplb_communicator.py:512 when validation fails: NIXL transfer failed. 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/distributed/eplb/eplb_communicator.py:512 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/94125c7fe3952c98. Report an issue: GitHub.