The Fix
pip install celery==4.4.3
Based on closed celery/celery issue #5598 · 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.
@@ -505,7 +505,7 @@ def on_failure(self, exc_info, send_failed_event=True, return_ok=False):
ack = self.task.acks_on_failure_or_timeout
if reject:
- requeue = not self.delivery_info.get('redelivered')
+ requeue = True
self.reject(requeue=requeue)
Option A — Upgrade to fixed release\npip install celery==4.4.3\nWhen NOT to use: This fix should not be applied if the behavior of requeuing tasks on worker loss is not desired.\n\n
Why This Fix Works in Production
- Trigger: - [x] I have included all related issues and possible duplicate issues in this issue
- Mechanism: The documentation incorrectly states that enabling task_reject_on_worker_lost can cause message loops
- Why the fix works: Fixes the documentation inconsistency regarding the task_reject_on_worker_lost configuration by ensuring tasks are requeued correctly when a worker is lost. (first fixed release: 4.4.3).
- 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
- The documentation incorrectly states that enabling task_reject_on_worker_lost can cause message loops
- Production symptom (often without a traceback): - [x] I have included all related issues and possible duplicate issues in this issue
Proof / Evidence
- GitHub issue: #5598
- Fix PR: https://github.com/celery/celery/pull/6103
- First fixed release: 4.4.3
- Reproduced locally: No (not executed)
- Last verified: 2026-02-09
- Confidence: 0.85
- Did this fix it?: Yes (upstream fix exists)
- Own content ratio: 0.71
Discussion
High-signal excerpts from the issue thread (symptoms, repros, edge-cases).
“<!-- Please fill this template entirely and do not erase parts of it. We reserve the right to close without a response bug reports which are incomplete. --> # Checklist <!-- To check an item on the list replace [ ] with [x]. --> - [x] I hav”
Failure Signature (Search String)
- - [x] I have included all related issues and possible duplicate issues in this issue
- or possible duplicates to this issue as requested by the checklist above.
Copy-friendly signature
Failure Signature
-----------------
- [x] I have included all related issues and possible duplicate issues in this issue
or possible duplicates to this issue as requested by the checklist above.
Error Message
Signature-only (no traceback captured)
Error Message
-------------
- [x] I have included all related issues and possible duplicate issues in this issue
or possible duplicates to this issue as requested by the checklist above.
What Broke
Tasks were being executed twice instead of being requeued correctly when a worker was lost.
Why It Broke
The documentation incorrectly states that enabling task_reject_on_worker_lost can cause message loops
Fix Options (Details)
Option A — Upgrade to fixed release Safe default (recommended)
pip install celery==4.4.3
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/6103
First fixed release: 4.4.3
Last verified: 2026-02-09. Validate in your environment.
When NOT to Use This Fix
- This fix should not be applied if the behavior of requeuing tasks on worker loss is not desired.
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 |
|---|---|
| 4.4.3 | Fixed |
Related Issues
No related fixes found.
Sources
We don’t republish the full GitHub discussion text. Use the links above for context.