langchain-ai/langgraph · error · ValueError

Missing required key(s) {missing_keys} in state_schema

Error message

Missing required key(s) {missing_keys} in state_schema

What it means

Error "Missing required key(s) {missing_keys} in state_schema" thrown in langchain-ai/langgraph.

Source

Thrown at libs/prebuilt/langgraph/prebuilt/chat_agent_executor.py:545

    if len(deprecated_kwargs) > 0:
        raise TypeError(
            f"create_react_agent() got unexpected keyword arguments: {deprecated_kwargs}"
        )

    if version not in ("v1", "v2"):
        raise ValueError(
            f"Invalid version {version}. Supported versions are 'v1' and 'v2'."
        )

    if state_schema is not None:
        required_keys = {"messages", "remaining_steps"}
        if response_format is not None:
            required_keys.add("structured_response")

        schema_keys = set(get_type_hints(state_schema))
        if missing_keys := required_keys - set(schema_keys):
            raise ValueError(f"Missing required key(s) {missing_keys} in state_schema")

    if state_schema is None:
        state_schema = (
            AgentStateWithStructuredResponse
            if response_format is not None
            else AgentState
        )

    llm_builtin_tools: list[dict] = []
    if isinstance(tools, ToolNode):
        tool_classes = list(tools.tools_by_name.values())
        tool_node = tools
    else:
        llm_builtin_tools = [t for t in tools if isinstance(t, dict)]
        tool_node = ToolNode([t for t in tools if not isinstance(t, dict)])
        tool_classes = list(tool_node.tools_by_name.values())

    is_dynamic_model = not isinstance(model, (str, Runnable)) and callable(model)

View on GitHub (pinned to 38031739e5)

When it happens

Trigger: Thrown at libs/prebuilt/langgraph/prebuilt/chat_agent_executor.py:545 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/80eac77f26efb0c1. Report an issue: GitHub.