Celery Unlike what doc states, --app does not behave like

The Fix

pip install celery==4.4.7

Based on closed celery/celery issue #4558 · PR/commit linked

Production note: Most teams hit this during upgrades or environment changes. Roll out with a canary and smoke critical endpoints (health, OpenAPI/docs) before 100%.

Jump to Verify Open PR/Commit

@@ -474,7 +474,7 @@ def prepare_parser(self, parser):
 
     def setup_app_from_commandline(self, argv):
-        preload_options = self.parse_preload_options(argv)
+        preload_options, remaining_options = self.parse_preload_options(argv)
         quiet = preload_options.get('quiet')

repro.py

$ pip install celery
$ cat > foo.py
from celery import Celery
app = Celery("foo")
^D

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==4.4.7\nWhen NOT to use: Do not use this fix if you rely on the specific behavior of argument ordering in your application.\n\n

Why This Fix Works in Production

Trigger: Unlike what doc states, --app does not behave like -A
Mechanism: The argument parsing for --app does not handle positional arguments correctly compared to -A
Why the fix works: Fixes the argument parsing issue where --app does not behave like -A, ensuring both options work consistently. (first fixed release: 4.4.7).

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 argument parsing for --app does not handle positional arguments correctly compared to -A
Production symptom (often without a traceback): Unlike what doc states, --app does not behave like -A

Proof / Evidence

GitHub issue: #4558
Fix PR: https://github.com/celery/celery/pull/6223
First fixed release: 4.4.7
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).

Jump to Sources Open on GitHub

“There is in fact a behavioral difference that depends on arguments position: celery worker -A foo works celery worker --app foo works celery -A foo…”

@hartym · 2018-08-15 · source

“do you have any suggested improvement in mind?”

@auvipy · 2018-08-15 · source

“(note that this bug is probably also affecting all other global options passed before the command name and that have arguments, like --broker BROKER, --result-backend…”

@hartym · 2018-08-19 · source

“(see https://github.com/celery/celery/blob/master/celery/bin/celery.py#L438:L473)”

@hartym · 2018-08-19 · source

Failure Signature (Search String)

Unlike what doc states, --app does not behave like -A
`celery --app foo worker` does not work and show celery usage

Copy-friendly signature

signature.txt

Failure Signature
-----------------
Unlike what doc states, --app does not behave like -A
`celery --app foo worker` does not work and show celery usage

Error Message

Signature-only (no traceback captured)

error.txt

Error Message
-------------
Unlike what doc states, --app does not behave like -A
`celery --app foo worker` does not work and show celery usage

Minimal Reproduction

repro.py

$ pip install celery
$ cat > foo.py
from celery import Celery
app = Celery("foo")
^D

What Broke

Using --app results in incorrect command output, leading to confusion and potential downtime.

Why It Broke

The argument parsing for --app does not handle positional arguments correctly compared to -A

Fix Options (Details)

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

pip install celery==4.4.7

When NOT to use: Do not use this fix if you rely on the specific behavior of argument ordering in your application.

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/6223

First fixed release: 4.4.7

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

When NOT to Use This Fix

Do not use this fix if you rely on the specific behavior of argument ordering in your application.

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
4.4.7	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 Unlike what doc states, --app does not behave like -A (Fix)