The Fix
pip install celery==5.5.0
Based on closed celery/celery issue #9218 · 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.
@@ -301,4 +301,5 @@ Johannes Faigle, 2024/06/18
Shamil Abdulaev, 2024/08/05
Nikos Atlas, 2024/08/26
+Marc Bresson, 2024/09/02
Narasux, 2024/09/09
diff --git a/celery/app/defaults.py b/celery/app/defaults.py
from celery.backends.database import SessionManager
app = Celery('celery', broker=BROKER_URL, backend=BACKEND_URL)
session = SessionManager()
engine = session.get_engine(app.backend.url)
session.prepare_models(engine)
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==5.5.0\nWhen NOT to use: This fix should not be used if lazy table creation is desired for backward compatibility.\n\n
Why This Fix Works in Production
- Trigger: - [x] I have included all related issues and possible duplicate issues
- Mechanism: Celery did not create database tables until the first task was executed, causing errors when querying the database
- Why the fix works: Added a non-lazy table creation option for database backends, allowing tables to be created at startup instead of waiting for the first task. (first fixed release: 5.5.0).
- 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
- Celery did not create database tables until the first task was executed, causing errors when querying the database
- Production symptom (often without a traceback): - [x] I have included all related issues and possible duplicate issues
Proof / Evidence
- GitHub issue: #9218
- Fix PR: https://github.com/celery/celery/pull/9228
- First fixed release: 5.5.0
- 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).
“<!-- 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.
Minimal Reproduction
from celery.backends.database import SessionManager
app = Celery('celery', broker=BROKER_URL, backend=BACKEND_URL)
session = SessionManager()
engine = session.get_engine(app.backend.url)
session.prepare_models(engine)
What Broke
Queries to the database failed due to missing tables, resulting in application errors.
Why It Broke
Celery did not create database tables until the first task was executed, causing errors when querying the database
Fix Options (Details)
Option A — Upgrade to fixed release Safe default (recommended)
pip install celery==5.5.0
Use when you can deploy the upstream fix. It is usually lower-risk than long-lived workarounds.
Option D — Guard side-effects with OnceOnly Guardrail for side-effects
Mitigate duplicate external side-effects under retries/timeouts/agent loops by gating the operation before calling external systems.
- Place OnceOnly between your code/agent and real side-effects (Stripe, emails, CRM, APIs).
- Use a stable key per side-effect (e.g., customer_id + action + idempotency_key).
- Fail-safe: configure fail-open vs fail-closed based on blast radius and spend risk.
Show example snippet (optional)
from onceonly import OnceOnly
import os
once = OnceOnly(api_key=os.environ["ONCEONLY_API_KEY"], fail_open=True)
# Stable idempotency key per real side-effect.
# Use a request id / job id / webhook delivery id / Stripe event id, etc.
event_id = "evt_..." # replace
key = f"stripe:webhook:{event_id}"
res = once.check_lock(key=key, ttl=3600)
if res.duplicate:
return {"status": "already_processed"}
# Safe to execute the side-effect exactly once.
handle_event(event_id)
Fix reference: https://github.com/celery/celery/pull/9228
First fixed release: 5.5.0
Last verified: 2026-02-09. Validate in your environment.
When NOT to Use This Fix
- This fix should not be used if lazy table creation is desired for backward compatibility.
- Do not use this to hide logic bugs or data corruption. Use it to block duplicate external side-effects and enforce tool permissions/spend caps.
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 |
|---|---|
| 5.5.0 | Fixed |
Related Issues
No related fixes found.
Sources
We don’t republish the full GitHub discussion text. Use the links above for context.