langchain-ai/langgraph · error · ValueError

Missing required config key '{runtime_key}' for '{self.name}

Error message

Missing required config key '{runtime_key}' for '{self.name}'.

What it means

Error "Missing required config key '{runtime_key}' for '{self.name}'." thrown in langchain-ai/langgraph.

Source

Thrown at libs/langgraph/langgraph/_internal/_runnable.py:415

                continue

            kw_value: Any = MISSING
            if kw == "config":
                kw_value = config
            elif kw == "error":
                kw_value = config.get(CONF, {}).get(CONFIG_KEY_NODE_ERROR, MISSING)
            elif runtime:
                if kw == "runtime":
                    kw_value = runtime
                else:
                    try:
                        kw_value = getattr(runtime, runtime_key)
                    except AttributeError:
                        pass

            if kw_value is MISSING:
                if default is inspect.Parameter.empty:
                    raise ValueError(
                        f"Missing required config key '{runtime_key}' for '{self.name}'."
                    )
                kw_value = default
            kwargs[kw] = kw_value

        if self.trace:
            callback_manager = get_callback_manager_for_config(config, self.tags)
            run_manager = callback_manager.on_chain_start(
                None,
                input,
                name=config.get("run_name") or self.get_name(),
                run_id=config.pop("run_id", None),
            )
            try:
                child_config = patch_config(config, callbacks=run_manager.get_child())
                # get the run
                for h in run_manager.handlers:
                    if isinstance(h, LangChainTracer):

View on GitHub (pinned to 38031739e5)

When it happens

Trigger: Thrown at libs/langgraph/langgraph/_internal/_runnable.py:415 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/3c9fb51774aaebfd. Report an issue: GitHub.