The Fix
pip install celery==4.4.0rc5
Based on closed celery/celery issue #4734 · PR/commit linked
Production note: Most teams hit this during upgrades or environment changes. Roll out with a canary and smoke critical endpoints (health, OpenAPI/docs) before 100%.
@@ -531,6 +531,27 @@ see :setting:`worker_redirect_stdouts`).
sys.stdout, sys.stderr = old_outs
+
+.. note::
+
LOGGING['loggers'] = {
'celery.app.trace': {
'handlers': [],
'level': 'INFO',
'propagate': True,
},
}
Re-run the minimal reproduction on your broken version, then apply the fix and re-run.
Option A — Upgrade to fixed release\npip install celery==4.4.0rc5\nWhen NOT to use: This fix is not applicable if the logging configuration is intentionally customized.\n\n
Why This Fix Works in Production
- Trigger: Celery 4.1: Logging task state is missing
- Mechanism: Logger propagation was disabled, preventing task completion logs from being emitted
- Why the fix works: Added documentation for logger propagation to address missing task state logs in Celery 4.1. (first fixed release: 4.4.0rc5).
- If left unfixed, the same config can fail only in production (env differences), causing startup failures or partial feature outages.
Why This Breaks in Prod
- Logger propagation was disabled, preventing task completion logs from being emitted
- Production symptom (often without a traceback): Celery 4.1: Logging task state is missing
Proof / Evidence
- GitHub issue: #4734
- Fix PR: https://github.com/celery/celery/pull/5325
- First fixed release: 4.4.0rc5
- 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).
“@stufan it looks like you have a ton of custom logging configured”
“I had the same issue when upgrading. I'm using Django and had to add this to my LOGGING dict for it to work again.”
“I definitely don't have this problem in my environment so I don't think it's systemic..”
“Just managed to test against the 4.2 release and issue still persists.”
Failure Signature (Search String)
- Celery 4.1: Logging task state is missing
- I managed to show the "succeeded" message on 4.1 by doing a very ugly hack inside celery/app/trace.py:info() function adding:
Copy-friendly signature
Failure Signature
-----------------
Celery 4.1: Logging task state is missing
I managed to show the "succeeded" message on 4.1 by doing a very ugly hack inside celery/app/trace.py:info() function adding:
Error Message
Signature-only (no traceback captured)
Error Message
-------------
Celery 4.1: Logging task state is missing
I managed to show the "succeeded" message on 4.1 by doing a very ugly hack inside celery/app/trace.py:info() function adding:
Minimal Reproduction
LOGGING['loggers'] = {
'celery.app.trace': {
'handlers': [],
'level': 'INFO',
'propagate': True,
},
}
What Broke
Task completion logs are missing, hindering debugging efforts.
Why It Broke
Logger propagation was disabled, preventing task completion logs from being emitted
Fix Options (Details)
Option A — Upgrade to fixed release Safe default (recommended)
pip install celery==4.4.0rc5
Use when you can deploy the upstream fix. It is usually lower-risk than long-lived workarounds.
Fix reference: https://github.com/celery/celery/pull/5325
First fixed release: 4.4.0rc5
Last verified: 2026-02-09. Validate in your environment.
When NOT to Use This Fix
- This fix is not applicable if the logging configuration is intentionally customized.
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
- Add a stress test that runs high-concurrency workloads and fails on thread dumps / blocked locks.
- Enable watchdog dumps in prod (faulthandler, thread dump endpoint) to capture deadlocks quickly.
Version Compatibility Table
| Version | Status |
|---|---|
| 4.4.0rc5 | Fixed |
Related Issues
No related fixes found.
Sources
We don’t republish the full GitHub discussion text. Use the links above for context.