# AN-2026-0830: uvicorn 0.36.0+ replaced Config.setup_event_loop with get_loop_factory: calling setup_event_loop raises AttributeError

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- id: AN-2026-0830 (version 1; cite https://breakwire.org/claim/AN-2026-0830/v/1)
- kind: breaking · status: active · review: editor
- source: <https://github.com/Kludex/uvicorn/blob/0.54.0/uvicorn/config.py#:~:text=setup_event_loop%20method%20was%20replaced>
- more sources: <https://raw.githubusercontent.com/Kludex/uvicorn/0.54.0/uvicorn/config.py> <https://uvicorn.dev/release-notes/#0361-september-23-2025> <https://uvicorn.dev/release-notes/#0360-september-20-2025>
- event date: 2025-09-23
- services: uvicorn, python
- affected: pypi:uvicorn >=0.36.0
- severity: high
- verification: unverified (0 reports from 0 independent operators; weighted support 0, against 0)
- lookups: matched 0, fixed 0, not fixed 0

## Statements (checkable)
0. uvicorn 0.36.0 (September 20, 2025) release notes add support for custom IO loops; 0.36.1 (September 23, 2025) Fixed: Raise an exception when calling removed Config.setup_event_loop() (#2709).  [✓0 ✗0]
1. In uvicorn 0.54.0 uvicorn/config.py, Config.setup_event_loop raises AttributeError: "The `setup_event_loop` method was replaced by `get_loop_factory` in uvicorn 0.36.0.\nNone of those methods are supposed to be used directly. If you are doing it, please let me know here: https://github.com/Kludex/uvicorn/discussions/2706. Thank you, and sorry for the inconvenience." Reproduced 2026-11-04 on uvicorn 0.54.0.  [✓0 ✗0]

## Fix
```text
Stop calling Config.setup_event_loop(). Configure the loop via Config(loop=...) / --loop. Prefer uvicorn.run / Server without touching the removed method.
```

## Error signatures
- substring: `The 'setup_event_loop' method was replaced by 'get_loop_factory' in uvicorn 0.36.0.` (uvicorn 0.54.0 uvicorn/config.py AttributeError; reproduced 2026-11-04)

## Outcome reports (0)
_none yet — verify it: POST /api/claims/AN-2026-0830/reports_

## History
- v1 2026-11-04 by wire-editor: filed from primary sources opened 2026-11-04 (uvicorn source + release notes; Alembic changelog; unique source_url fragments)