Celery Django fixup appends to PYTHONPATH instead of

The Fix

pip install celery==4.4.0rc5

Based on closed celery/celery issue #5347 · 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

@@ -57,8 +57,10 @@ def __init__(self, app):
 
     def install(self):
-        # Need to add project directory to path
-        sys.path.append(os.getcwd())
+        # Need to add project directory to path.

repro.py

# When going through celery CLI
sys.path == ['/Users/lverney/.local/share/virtualenvs/dissemin3/bin', '/Users/lverney/.local/share/virtualenvs/dissemin3/lib/python36.zip', '/Users/lverney/.local/share/virtualenvs/dissemin3/lib/python3.6', '/Users/lverney/.local/share/virtualenvs/dissemin3/lib/python3.6/lib-dynload', '/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6', '/Users/lverney/.local/share/virtualenvs/dissemin3/lib/python3.6/site-packages', '/Users/lverney/.local/share/virtualenvs/dissemin3/src/django-allauth', '/Users/lverney/tmp/dissemin']

# Without celery
sys.path == ['', '/Users/lverney/.local/share/virtualenvs/dissemin3/lib/python36.zip', '/Users/lverney/.local/share/virtualenvs/dissemin3/lib/python3.6', '/Users/lverney/.local/share/virtualenvs/dissemin3/lib/python3.6/lib-dynload', '/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6', '/Users/lverney/.local/share/virtualenvs/dissemin3/lib/python3.6/site-packages', '/Users/lverney/.local/share/virtualenvs/dissemin3/src/django-allauth']

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==4.4.0rc5\nWhen NOT to use: Do not use this fix if the order of module loading is intentionally designed to prioritize system modules.\n\nOption C — Workaround\nFor people experiencing this issue, `PYTHONPATH=$(pwd) celery …` is a workaround.\nWhen NOT to use: Do not use this fix if the order of module loading is intentionally designed to prioritize system modules.\n\n

Why This Fix Works in Production

Trigger: I traced this issue back to [this `sys.path`…
Mechanism: Fixes the issue by prepending the project directory to the system path instead of appending it, ensuring local modules have precedence over system ones.
Why the fix works: Fixes the issue by prepending the project directory to the system path instead of appending it, ensuring local modules have precedence over system ones. (first fixed release: 4.4.0rc5).

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

Shows up under Python 3.6 in real deployments (not just unit tests).
Production symptom (often without a traceback): I traced this issue back to [this `sys.path` tweak](https://github.com/celery/celery/blob/072dab85261599234341cc714b0d6f0caca20f00/celery/fixups/django.py#L60-L61), which is actually **appending** local path instead of prepending it.

Proof / Evidence

GitHub issue: #5347
Fix PR: https://github.com/celery/celery/pull/5355
First fixed release: 4.4.0rc5
Reproduced locally: No (not executed)
Last verified: 2026-02-09
Confidence: 0.85
Did this fix it?: Yes (upstream fix exists)
Own content ratio: 0.47

Discussion

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

Jump to Sources Open on GitHub

“@auvipy fixing is easy - use prepend instead of append. I am more worried about the sort of testing you would expect for that kind…”

@wetneb · 2019-02-22 · source

“@auvipy @wetneb This is throwing an error. Lists don't have 'prepend' methods. Instead, please change sys.path.prepend(os.getcwd()) to sys.path.insert(0, os.getcwd())”

@richkirsch · 2019-02-22 · source

“@richkirsch yes this was my fault! This was fixed, just git pull again.”

@wetneb · 2019-02-22 · source

Failure Signature (Search String)

I traced this issue back to [this `sys.path` tweak](https://github.com/celery/celery/blob/072dab85261599234341cc714b0d6f0caca20f00/celery/fixups/django.py#L60-L61), which is
This is throwing an error. Lists don't have 'prepend' methods.

Copy-friendly signature

signature.txt

Failure Signature
-----------------
I traced this issue back to [this `sys.path` tweak](https://github.com/celery/celery/blob/072dab85261599234341cc714b0d6f0caca20f00/celery/fixups/django.py#L60-L61), which is actually **appending** local path instead of prepending it.
This is throwing an error. Lists don't have 'prepend' methods.

Error Message

Signature-only (no traceback captured)

error.txt

Error Message
-------------
I traced this issue back to [this `sys.path` tweak](https://github.com/celery/celery/blob/072dab85261599234341cc714b0d6f0caca20f00/celery/fixups/django.py#L60-L61), which is actually **appending** local path instead of prepending it.
This is throwing an error. Lists don't have 'prepend' methods.

Minimal Reproduction

repro.py

# When going through celery CLI
sys.path == ['/Users/lverney/.local/share/virtualenvs/dissemin3/bin', '/Users/lverney/.local/share/virtualenvs/dissemin3/lib/python36.zip', '/Users/lverney/.local/share/virtualenvs/dissemin3/lib/python3.6', '/Users/lverney/.local/share/virtualenvs/dissemin3/lib/python3.6/lib-dynload', '/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6', '/Users/lverney/.local/share/virtualenvs/dissemin3/lib/python3.6/site-packages', '/Users/lverney/.local/share/virtualenvs/dissemin3/src/django-allauth', '/Users/lverney/tmp/dissemin']

# Without celery
sys.path == ['', '/Users/lverney/.local/share/virtualenvs/dissemin3/lib/python36.zip', '/Users/lverney/.local/share/virtualenvs/dissemin3/lib/python3.6', '/Users/lverney/.local/share/virtualenvs/dissemin3/lib/python3.6/lib-dynload', '/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6', '/Users/lverney/.local/share/virtualenvs/dissemin3/lib/python3.6/site-packages', '/Users/lverney/.local/share/virtualenvs/dissemin3/src/django-allauth']

Environment

Python: 3.6

What Broke

Celery CLI loads system modules instead of local ones, leading to unexpected behavior.

Fix Options (Details)

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

pip install celery==4.4.0rc5

When NOT to use: Do not use this fix if the order of module loading is intentionally designed to prioritize system modules.

Use when you can deploy the upstream fix. It is usually lower-risk than long-lived workarounds.

Option C — Workaround Temporary workaround

For people experiencing this issue, `PYTHONPATH=$(pwd) celery …` is a workaround.

When NOT to use: Do not use this fix if the order of module loading is intentionally designed to prioritize system modules.

Use only if you cannot change versions today. Treat this as a stopgap and remove once upgraded.

Fix reference: https://github.com/celery/celery/pull/5355

First fixed release: 4.4.0rc5

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

When NOT to Use This Fix

Do not use this fix if the order of module loading is intentionally designed to prioritize system modules.

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
4.4.0rc5	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 Django fixup appends to PYTHONPATH instead of prepending (Fix)