By Bernat Sampera 1 min read Follow:

Common langgraph errors and how to solve them.

Understand what each of these errors and learn how to fix it. This is a summary of all the error messages I get in langgrapgh and track how it's been solved to avoid doing the error again

  1. "Invalid parameter: messages with role \'tool\' must be a response to a preceeding message with \'tool_calls\'."
    Pretty self explanatory, an AI decides which tool will be called, and this happens by adding to the message list a new entry with x tool_calls, then the url is called and the results are added to the message list. If the message list doesn’t have something like add_messages, it can be that the tool response overwrites the original message with tool_calls which causes this error.

    Solution: Have a message list with [AI( with tool_calls X ), ToolOutput ( Response from Tool Call X ) ]

  2. An assistant message with \'tool_calls\' must be followed by tool messages responding to each \'tool_call_id\'. The following tool_call_ids did not have response messages:
    Similar as before but a bit different. This happens when there is an AI message with a tool call, and then there is no other message of the ToolOutput

Let's connect !!

Get in touch if you want updates, examples, and insights on how AI agents, Langchain and more are evolving and where they’re going next.