langchain-ai/langgraph · error · KeyError

{state_field}

Error message

{state_field}

What it means

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

Source

Thrown at libs/prebuilt/langgraph/prebuilt/tool_node.py:1397

                        f"Invalid input to ToolNode. Tool {tool_call['name']} requires "
                        f"graph state dict as input."
                    )
                    if any(state_field for state_field in injected.state.values()):
                        required_fields_str = ", ".join(f for f in required_fields if f)
                        err_msg += (
                            f" State should contain fields {required_fields_str}."
                        )
                    raise ValueError(err_msg)

            # Extract state values
            if isinstance(state, dict):
                for tool_arg, state_field in injected.state.items():
                    if not state_field:
                        injected_args[tool_arg] = state
                    elif state_field in state:
                        injected_args[tool_arg] = state[state_field]
                    elif tool_arg not in injected._optional_state_args:
                        raise KeyError(state_field)
            else:
                for tool_arg, state_field in injected.state.items():
                    if not state_field:
                        injected_args[tool_arg] = state
                    elif hasattr(state, state_field):
                        injected_args[tool_arg] = getattr(state, state_field)
                    elif tool_arg not in injected._optional_state_args:
                        raise AttributeError(state_field)

        # Inject store
        if injected.store:
            if tool_runtime.store is None:
                msg = (
                    "Cannot inject store into tools with InjectedStore annotations - "
                    "please compile your graph with a store."
                )
                raise ValueError(msg)
            injected_args[injected.store] = tool_runtime.store

View on GitHub (pinned to 38031739e5)

When it happens

Trigger: Thrown at libs/prebuilt/langgraph/prebuilt/tool_node.py:1397 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/4873124edfea3c6c. Report an issue: GitHub.