The Fix
Upgrade to version 0.11.4 or later.
Based on closed Kludex/uvicorn issue #614 · PR/commit linked
Production note: This usually shows up under retries/timeouts. Treat it as a side-effect risk until you can verify behavior with a canary + real traffic.
@@ -20,10 +20,12 @@ def __init__(self, *args, **kwargs):
logger.handlers = self.log.error_log.handlers
logger.setLevel(self.log.error_log.level)
+ logger.propagate = False
logger = logging.getLogger("uvicorn.access")
import logging
from starlette.applications import Starlette
logging.error('TEST')
app = Starlette()
Re-run the minimal reproduction on your broken version, then apply the fix and re-run.
Option A — Upgrade to fixed release\nUpgrade to version 0.11.4 or later.\nWhen NOT to use: This fix should not be applied if the application relies on root logger propagation for logging.\n\n
Why This Fix Works in Production
- Trigger: ERROR:root:TEST 1 -- LOGGING ERROR
- Mechanism: Uvicorn logs are duplicated when using Gunicorn due to root logger propagation
- Why the fix works: Fixes an integration issue with Gunicorn where uvicorn logs would be duplicated if root handlers are present. (first fixed release: 0.11.4).
- If left unfixed, retries/timeouts can trigger duplicate external side-effects (double charges, duplicate emails, repeated writes).
Why This Breaks in Prod
- Uvicorn logs are duplicated when using Gunicorn due to root logger propagation
- Surfaces as: ERROR:root:TEST 1 -- LOGGING ERROR
Proof / Evidence
- GitHub issue: #614
- Fix PR: https://github.com/kludex/uvicorn/pull/623
- First fixed release: 0.11.4
- Reproduced locally: No (not executed)
- Last verified: 2026-02-09
- Confidence: 0.85
- Did this fix it?: Yes (upstream fix exists)
- Own content ratio: 0.70
Discussion
High-signal excerpts from the issue thread (symptoms, repros, edge-cases).
“Yup, found the fix: add .propagate = False to uvicorn's loggers”
“In terms of prior art, Uvicorn already updates its logging to use the handlers that Gunicorn provides: https://github.com/encode/uvicorn/blob/fdb89e9cc942aaf38eb57b71172d02c868502aa3/uvicorn/workers.py#L20-L26 That being said… when I try out…”
“Here is the work around I came up with for uniform gunicorn style logging with gunicorn -k uvicorn.workers.UvicornWorker ... and uvicorn ....”
Failure Signature (Search String)
- ERROR:root:TEST 1 -- LOGGING ERROR
Error Message
Stack trace
Error Message
-------------
ERROR:root:TEST 1 -- LOGGING ERROR
Stack trace
Error Message
-------------
ERROR:foo:TEST 3 -- FOO LOGGER ERROR
Stack trace
Error Message
-------------
ERROR:root:TEST
Minimal Reproduction
import logging
from starlette.applications import Starlette
logging.error('TEST')
app = Starlette()
What Broke
Users experience duplicate log entries when running Uvicorn with Gunicorn.
Why It Broke
Uvicorn logs are duplicated when using Gunicorn due to root logger propagation
Fix Options (Details)
Option A — Upgrade to fixed release Safe default (recommended)
Upgrade to version 0.11.4 or later.
Use when you can deploy the upstream fix. It is usually lower-risk than long-lived workarounds.
Fix reference: https://github.com/kludex/uvicorn/pull/623
First fixed release: 0.11.4
Last verified: 2026-02-09. Validate in your environment.
When NOT to Use This Fix
- This fix should not be applied if the application relies on root logger propagation for logging.
Verify Fix
Re-run the minimal reproduction on your broken version, then apply the fix and re-run.
Did This Fix Work in Your Case?
Quick signal helps us prioritize which fixes to verify and improve.
Prevention
- Capture the exact failing error string in logs and tests so you can reproduce via a minimal script.
- Pin production dependencies and upgrade only with a reproducible test that hits the failing path.
Version Compatibility Table
| Version | Status |
|---|---|
| 0.11.4 | Fixed |
Related Issues
No related fixes found.
Sources
We don’t republish the full GitHub discussion text. Use the links above for context.