langchain-ai/langgraph · error · Exception

{response['__error__'].get('error')}…

Error message

{response['__error__'].get('error')}: {response['__error__'].get('message')}

What it means

Server-error propagation in the async runs client: when raise_error is enabled and the streamed response dict contains an '__error__' envelope, the client re-raises it locally as an exception combining the server's error name and message. It is a transport-level wrapper, not a local validation failure.

Solutions

1. Inspect the error name/message for the server-side cause (e.g. graph not found, invalid input) and fix the request
2. Pass on_run_error or check the run's status to handle failures without raising
3. Retry transient server errors once the underlying cause is resolved

When it happens

Trigger: Thrown at libs/sdk-py/langgraph_sdk/_async/runs.py:849 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/38eb4da8541fdd31. Report an issue: GitHub.

Appendix: source

Thrown at libs/sdk-py/langgraph_sdk/_async/runs.py:849

            """Callback function to handle the response."""
            if on_run_created and (metadata := _get_run_metadata_from_response(res)):
                on_run_created(metadata)

        response = await self.http.request_reconnect(
            endpoint,
            "POST",
            json={k: v for k, v in payload.items() if v is not None},
            params=params,
            headers=headers,
            on_response=on_response if on_run_created else None,
        )
        if (
            raise_error
            and isinstance(response, dict)
            and "__error__" in response
            and isinstance(response["__error__"], dict)
        ):
            raise Exception(
                f"{response['__error__'].get('error')}: {response['__error__'].get('message')}"
            )
        return response

    async def list(
        self,
        thread_id: str,
        *,
        limit: int = 10,
        offset: int = 0,
        status: RunStatus | None = None,
        select: builtins.list[RunSelectField] | None = None,
        headers: Mapping[str, str] | None = None,
        params: QueryParamTypes | None = None,
    ) -> builtins.list[Run]:
        """List runs.

        Args:

View on GitHub (pinned to 38031739e5)