Celery non working example of using celery

The Fix

pip install celery==5.3.0b2

Based on closed celery/celery issue #7750 · 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

@@ -160,7 +160,8 @@ Example:
         def mul(x, y):
             return x * y
-
+        
+        celery_worker.reload()

repro.py

from celery import Celery
from celery.contrib.testing.worker import TestWorkController
from celery.result import AsyncResult
import pytest

@pytest.fixture
def celery_app(celery_app: Celery):

    @celery_app.task(name='xyz')
    def mul(x, y):
        """register a task named 'test_create_task.mul'"""
        return x * y

    return celery_app



def test_create_task(celery_app: Celery, celery_worker: TestWorkController):    
    result: AsyncResult = celery_app.send_task('xyz', kwargs = {"x": 2, "y": 2})
    result.wait()
    assert result.get() == 4

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==5.3.0b2\nWhen NOT to use: Do not use this fix if the task registration is handled elsewhere.\n\n

Why This Fix Works in Production

Trigger: non working example of using celery_worker pytest fixture (celery.exception.NotRegistered)
Mechanism: The task was not registered in the worker due to a missing reload call
Why the fix works: Fixes a non-working example in the documentation for using the celery_worker pytest fixture by adding a call to reload the worker. (first fixed release: 5.3.0b2).

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

The task was not registered in the worker due to a missing reload call
Production symptom (often without a traceback): non working example of using celery_worker pytest fixture (celery.exception.NotRegistered)

Proof / Evidence

GitHub issue: #7750
Fix PR: https://github.com/celery/celery/pull/7857
First fixed release: 5.3.0b2
Reproduced locally: No (not executed)
Last verified: 2026-02-09
Confidence: 0.85
Did this fix it?: Yes (upstream fix exists)
Own content ratio: 0.53

Discussion

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

Jump to Sources Open on GitHub

“Hey @hq9000 :wave:, Thank you for opening an issue”

@open-collective-bot · 2022-09-09 · source

“would you mind sending a patch to improve this?”

@auvipy · 2022-09-09 · source

“> would you mind sending a patch to improve this? will do in a couple of days”

@hq9000 · 2022-09-09 · source

Failure Signature (Search String)

non working example of using celery_worker pytest fixture (celery.exception.NotRegistered)
- [x] I have included all related issues and possible duplicate issues in this issue

Copy-friendly signature

signature.txt

Failure Signature
-----------------
non working example of using celery_worker pytest fixture (celery.exception.NotRegistered)
- [x] I have included all related issues and possible duplicate issues in this issue

Error Message

Signature-only (no traceback captured)

error.txt

Error Message
-------------
non working example of using celery_worker pytest fixture (celery.exception.NotRegistered)
- [x] I have included all related issues and possible duplicate issues in this issue

Minimal Reproduction

repro.py

from celery import Celery
from celery.contrib.testing.worker import TestWorkController
from celery.result import AsyncResult
import pytest

@pytest.fixture
def celery_app(celery_app: Celery):

    @celery_app.task(name='xyz')
    def mul(x, y):
        """register a task named 'test_create_task.mul'"""
        return x * y

    return celery_app



def test_create_task(celery_app: Celery, celery_worker: TestWorkController):    
    result: AsyncResult = celery_app.send_task('xyz', kwargs = {"x": 2, "y": 2})
    result.wait()
    assert result.get() == 4

Why It Broke

The task was not registered in the worker due to a missing reload call

Fix Options (Details)

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

pip install celery==5.3.0b2

When NOT to use: Do not use this fix if the task registration is handled elsewhere.

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/7857

First fixed release: 5.3.0b2

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

When NOT to Use This Fix

Do not use this fix if the task registration is handled elsewhere.

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
5.3.0b2	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 non working example of using celery_worker pytest fixture (celery.exception.NotRegistered) (Fix)