---
title: "MGS9028: streaming unsupported"
description: An event stream was asked of a response writer that cannot flush, such as one wrapped by a proxy or middleware that buffers. Answered 500.
tags: [MGS9028, api, sse, streaming, "500"]
---

# MGS9028: streaming unsupported

The server answered `500 internal` because the route streams Server-Sent Events
and the response writer it was handed cannot flush.

```text
[MGS9028] the response writer cannot stream; a proxy or middleware is buffering it
  see: .../MGS9028.md
```

## Why

An event stream is useless if a layer holds it until the response ends. The
route checks for the ability to flush before it writes a header, and refuses
rather than open a stream nobody will receive.

## Resolution

Reach the server directly on its loopback address, or configure the layer in
front of it not to buffer (`X-Accel-Buffering: no` for nginx, response
buffering off for other proxies).

## What this is not

- **Not an internal read failure.** That is [MGS9027](MGS9027.md).