Celery @app.task should copy __annotations_

The Fix

pip install celery==5.0.1

Based on closed celery/celery issue #6186 · 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.

Jump to Verify Open PR/Commit

@@ -428,6 +428,7 @@ def _task_from_fun(self, fun, name=None, base=None, bind=False, **options):
                 '__doc__': fun.__doc__,
                 '__module__': fun.__module__,
+                '__annotations__': fun.__annotations__,
                 '__header__': staticmethod(head_from_fun(fun, bound=bind)),
                 '__wrapped__': run}, **options))()

repro.py

@functools.wraps(decorated_function, assigned=('__annotations__',))
@celery_app.task(bind=True, base=base, priority=priority, name=name)
def task(): ...

verify

Re-run the minimal reproduction on your broken version, then apply the fix and re-run.

fix.md

Option A — Upgrade to fixed release\npip install celery==5.0.1\nWhen NOT to use: Do not use if it changes public behavior or if the failure cannot be reproduced.\n\n

Why This Fix Works in Production

Trigger: - [x] I have included all related issues and possible duplicate issues
Mechanism: The task decorator does not copy __annotations__ from the decorated function
Why the fix works: Enables getting type hints for tasks by copying __annotations__ when creating tasks. (first fixed release: 5.0.1).

Production impact:

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

Triggered by an upgrade/regression window: 3.0–3.6 breaks; 5.0.1 is the first fixed release.
Shows up under Python 3.0 in real deployments (not just unit tests).
The task decorator does not copy __annotations__ from the decorated function
Production symptom (often without a traceback): - [x] I have included all related issues and possible duplicate issues

Proof / Evidence

GitHub issue: #6186
Fix PR: https://github.com/celery/celery/pull/6419
First fixed release: 5.0.1
Affected versions: 3.0–3.6
Reproduced locally: No (not executed)
Last verified: 2026-02-09
Confidence: 0.75
Did this fix it?: Yes (upstream fix exists)
Own content ratio: 0.62

Discussion

High-signal excerpts from the issue thread (symptoms, repros, edge-cases).

Jump to Sources Open on GitHub

“#6419 is open”

@davidparsson · 2020-10-16 · confirmation · source

“Thanks! Please let me know if help is needed for this to be implemented.”

@davidparsson · 2020-06-24 · source

“for celery 4.5 which will be python 3.6+ only”

@auvipy · 2020-06-25 · source

“For anyone finding this before it's fixed, I have the following work-around:”

@davidparsson · 2020-09-25 · source

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

signature.txt

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.txt

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

repro.py

@functools.wraps(decorated_function, assigned=('__annotations__',))
@celery_app.task(bind=True, base=base, priority=priority, name=name)
def task(): ...

Environment

Python: 3.0

Why It Broke

The task decorator does not copy __annotations__ from the decorated function

Fix Options (Details)

Option A — Upgrade to fixed release Safe default (recommended)

pip install celery==5.0.1

When NOT to use: Do not use if it changes public behavior or if the failure cannot be reproduced.

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/6419

First fixed release: 5.0.1

Last verified: 2026-02-09. Validate in your environment.

When NOT to Use This Fix

Do not use if it changes public behavior or if the failure cannot be reproduced.

Verify Fix

verify

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
3.0	Broken
3.6	Broken
5.0.1	Fixed

Related Issues

No related fixes found.

Cluster: celery:configuration-error Celery hub Celery best practices All hubs All clusters

Related clusters: Data consistency Duplicates Duplicate processing

Sources

We don’t republish the full GitHub discussion text. Use the links above for context.

Celery @app.task should copy __annotations__ from the task function like @functools.wraps (Fix)