# RuntimeError: No response returned.

- **ID:** `python/starlette-streaming-response-generator-error`
- **Domain:** python
- **Category:** runtime_error
- **Verification:** ai_generated
- **Fix Rate:** 80%

## Root Cause

A middleware or dependency returns None instead of a Response, or a route forgets to return, so Starlette finds no response to send.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| 3.x | active | — | — |

## Workarounds

1. **** (92% success)
   ```
   Ensure every code path returns a Response:
return JSONResponse({'ok': True})
   ```
2. **** (88% success)
   ```
   In middleware, always call await call_next(request) and return its result.
   ```

## Dead Ends

- **** — The error is raised at the ASGI layer where the handler may not apply. (70% fail)
- **** — Masks the real bug; the route still doesn't produce intended output. (75% fail)