Developer shares two common SSE streaming pitfalls when deploying RAG apps to production

A developer building a Retrieval-Augmented Generation (RAG) application encountered two production issues that did not appear during local testing. The backend was built using FastAPI with Server-Sent Events (SSE) to stream large language model responses token by token. In production, nginx was silently buffering the SSE stream, which was resolved by setting proxy_buffering off after roughly two hours of debugging. Additionally, the LLM API was found to return an empty_retrieval event when no documents matched a query, a case the developer had not initially handled. The post highlights the importance of accounting for proxy configurations and edge-case API responses when deploying streaming LLM applications.