The Fix
pip install celery==5.2.0rc2
Based on closed celery/celery issue #8687 · 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.
@@ -2,6 +2,7 @@
from time import monotonic
+from greenlet import GreenletExit
from kombu.asynchronous import timer as _timer
Option A — Upgrade to fixed release\npip install celery==5.2.0rc2\nWhen NOT to use: This fix is not applicable for other concurrency backends like prefork.\n\n
Why This Fix Works in Production
- Trigger: - [x] I have included all related issues and possible duplicate issues
- Mechanism: Current implementation of TaskPool based on gevent does not support terminating jobs
- Why the fix works: Implemented job termination for the gevent concurrency backend in Celery, addressing the NotImplementedError when attempting to revoke jobs. (first fixed release: 5.2.0rc2).
- If left unfixed, retries/timeouts can trigger duplicate external side-effects (double charges, duplicate emails, repeated writes).
Why This Breaks in Prod
- Current implementation of TaskPool based on gevent does not support terminating jobs
- Production symptom (often without a traceback): - [x] I have included all related issues and possible duplicate issues
Proof / Evidence
- GitHub issue: #8687
- Fix PR: https://github.com/celery/celery/pull/6917
- First fixed release: 5.2.0rc2
- Reproduced locally: No (not executed)
- Last verified: 2026-02-09
- Confidence: 0.85
- Did this fix it?: Yes (upstream fix exists)
- Own content ratio: 0.79
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 feature requests which are incomplete. --> # Checklist <!-- To check an item on the list replace [ ] with [x]. --> - [x]”
Failure Signature (Search String)
- - [x] I have included all related issues and possible duplicate issues
- 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
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
or possible duplicates to this issue as requested by the checklist above.
What Broke
Revoking jobs with terminate=True raises NotImplementedError while tasks continue to run.
Why It Broke
Current implementation of TaskPool based on gevent does not support terminating jobs
Fix Options (Details)
Option A — Upgrade to fixed release Safe default (recommended)
pip install celery==5.2.0rc2
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/6917
First fixed release: 5.2.0rc2
Last verified: 2026-02-09. Validate in your environment.
When NOT to Use This Fix
- This fix is not applicable for other concurrency backends like prefork.
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 |
|---|---|
| 5.2.0rc2 | Fixed |
Related Issues
No related fixes found.
Sources
We don’t republish the full GitHub discussion text. Use the links above for context.