langgraph/docs/docs/troubleshooting/errors/INVALID_CHAT_HISTORY.md

INVALID_CHAT_HISTORY

:::python This error is raised in the prebuilt @[create_react_agent][create_react_agent] when the call_model graph node receives a malformed list of messages. Specifically, it is malformed when there are AIMessages with tool_calls (LLM requesting to call a tool) that do not have a corresponding ToolMessage (result of a tool invocation to return to the LLM). :::

:::js This error is raised in the prebuilt @[createReactAgent][create_react_agent] when the callModel graph node receives a malformed list of messages. Specifically, it is malformed when there are AIMessages with tool_calls (LLM requesting to call a tool) that do not have a corresponding ToolMessage (result of a tool invocation to return to the LLM). :::

There could be a few reasons you're seeing this error:

:::python

1. You manually passed a malformed list of messages when invoking the graph, e.g. graph.invoke({'messages': [AIMessage(..., tool_calls=[...])]})

2. The graph was interrupted before receiving updates from the tools node (i.e. a list of ToolMessages) and you invoked it with an input that is not None or a ToolMessage, e.g. graph.invoke({'messages': [HumanMessage(...)]}, config).

   This interrupt could have been triggered in one of the following ways:

   • You manually set interrupt_before = ['tools'] in create_react_agent
   • One of the tools raised an error that wasn't handled by the @[ToolNode][ToolNode] ("tools")

:::

:::js

1. You manually passed a malformed list of messages when invoking the graph, e.g. graph.invoke({messages: [new AIMessage({..., tool_calls: [...]})]})

2. The graph was interrupted before receiving updates from the tools node (i.e. a list of ToolMessages) and you invoked it with an input that is not null or a ToolMessage, e.g. graph.invoke({messages: [new HumanMessage(...)]}, config).

   This interrupt could have been triggered in one of the following ways:

   • You manually set interruptBefore: ['tools'] in createReactAgent
   • One of the tools raised an error that wasn't handled by the @[ToolNode][ToolNode] ("tools")

:::

Troubleshooting

To resolve this, you can do one of the following:

1. Don't invoke the graph with a malformed list of messages
2. In case of an interrupt (manual or due to an error) you can:

:::python

• provide ToolMessages that match existing tool calls and call graph.invoke({'messages': [ToolMessage(...)]}). NOTE: this will append the messages to the history and run the graph from the START node.

  • manually update the state and resume the graph from the interrupt:

      1. get the list of most recent messages from the graph state with `graph.get_state(config)`
      2. modify the list of messages to either remove unanswered tool calls from AIMessages
    

or add ToolMessages with tool_call_ids that match unanswered tool calls 3. call graph.update_state(config, {'messages': ...}) with the modified list of messages 4. resume the graph, e.g. call graph.invoke(None, config) :::

:::js

• provide ToolMessages that match existing tool calls and call graph.invoke({messages: [new ToolMessage(...)]}). NOTE: this will append the messages to the history and run the graph from the START node.

  • manually update the state and resume the graph from the interrupt:

      1. get the list of most recent messages from the graph state with `graph.getState(config)`
      2. modify the list of messages to either remove unanswered tool calls from AIMessages
    

or add ToolMessages with toolCallIds that match unanswered tool calls 3. call graph.updateState(config, {messages: ...}) with the modified list of messages 4. resume the graph, e.g. call graph.invoke(null, config) :::