When a specific node fails due to an API timeout, I want the system to retry that specific step rather than restarting the whole process. How can LangGraph handle error transitions? I'm looking for a way to define "catch-all" edges that direct the flow to a recovery node.
3 answers
You can manage this by defining a conditional edge that checks for an "error" key in your state. If a node execution fails, you catch the exception within the node function and update the state with the error details. The conditional edge then routes the flow to a specialized "retry_node" or back to the original node. For more advanced cases, you can use the built-in retry policies available in the newer versions, which allow for exponential backoff. This ensures that transient network issues don't crash your entire multi-step agentic workflow.
If we route back to the same node for a retry, how do we prevent an infinite loop if the error is permanent?
The best way is to use a try-except block inside your node function and update the state accordingly.
That is a solid start, and combined with conditional edges, it makes the workflow very resilient to external API fluctuations.
You should include a "retry_count" in your state. Increment it each time you hit the error node. If it exceeds 3, route the edge to a final "failure_node" to alert a human.