langchain-ai/langgraph · error · HostBackendError

{err}

Error message

{err}

What it means

Error "{err}" thrown in langchain-ai/langgraph.

Source

Thrown at libs/cli/langgraph_cli/host_backend.py:62

    def _request(
        self,
        method: str,
        path: str,
        payload: dict[str, Any] | None = None,
        params: dict[str, Any] | None = None,
    ) -> Any:
        try:
            resp = self._client.request(method, path, json=payload, params=params)
            resp.raise_for_status()
        except httpx.HTTPStatusError as err:
            detail = err.response.text or str(err.response.status_code)
            raise HostBackendError(
                f"{method} {path} failed with status {err.response.status_code}: {detail}",
                status_code=err.response.status_code,
            ) from None
        except httpx.TransportError as err:
            raise HostBackendError(str(err)) from None

        if not resp.content:
            return None
        try:
            return resp.json()
        except ValueError as err:
            raise HostBackendError(
                f"Failed to decode response from {path}: {err}"
            ) from None

    def create_deployment(
        self,
        name: str,
        deployment_type: str,
        source: str,
        config_path: str | None = None,
        secrets: list[dict[str, str]] | None = None,
    ) -> dict[str, Any]:

View on GitHub (pinned to 38031739e5)

When it happens

Trigger: Thrown at libs/cli/langgraph_cli/host_backend.py:62 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of langchain-ai/langgraph@38031739e5 (2026-08-26). Data as JSON: /api/errors/dbf3604140ff38ef. Report an issue: GitHub.