Azure Function Response Streaming raises 'The response ended prematurely.'

Question

I am facing an error with Azure Function Response Streaming for our Langgraph code.

Azure Region: East US

We have two Azure Functions:

• async_bot_execute
• sync_bot_execute

async_agent_ execute calls langgraph agent asynchronously, so as to stream the response in real time(as and when the agent model streams the final response)

sync_agent_ execute calls langgraph agent synchronously and streams the final agent response token by token (not in real time ,only after the complete response is generated)

Both the azure functions are working as expected in the local environment. But after deployment to azure (python 3.11,linux), on both standard and premium, only sync_agent_execute streams the response and async_agent_execute raises 'The response ended prematurely.' error.

Please let me know if any more details are required.

Answer 1

The message "The response ended prematurely." usually indicates that the server closed the connection before the response was complete. This can happen if the server is terminating the connection prematurely or if there is a network issue. Since the issue is consistent with async-approach, I believe the connection is getting closed because of a time-out

If your function apps are HTTP-Triggered, 230 seconds is the maximum amount of time the function can take to respond to a request. If the asynchronous operation takes a long time to complete, the function instance may be terminated by the Azure Functions runtime before the operation completes. This is because Azure Functions are designed to be stateless and can be terminated at any time.

For longer processing times, consider using the Durable Functions async pattern or defer the actual work and return an immediate response.

Here is a sample implementation for your reference that provides an approach to use LangChain with Azure functions

• Azure Functions - LangChain with Azure OpenAI and ChatGPT (Python v2 Function)