library · inferred from evidence
RootListenersTracer
A tracer component in LangChain responsible for handling chain events, including on_chain_end callbacks.
- Error in RootListenersTracer.on_chain_end callback: KeyError('answer') while streaming a RAG chain
Building a conversational RAG chatbot with create_retrieval_chain wrapped in RunnableWithMessageHistory (input_messages_key="input", history_messages_key="chat_history", output_messages_key="answer"). Calling astream() on the chain printed