Celery `celery multi`creates xxx

The Fix

pip install celery==5.0

Based on closed celery/celery issue #6426 · 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

@@ -94,6 +94,11 @@ def detach(path, argv, logfile=None, pidfile=None, uid=None,
     """Detach program by argv."""
     fake = 1 if C_FAKEFORK else fake
+    # `detached()` will attempt to touch the logfile to confirm that error
+    # messages won't be lost after detaching stdout/err, but this means we need
+    # to pre-format it rather than relying on `setup_logging_subsystem()` like

repro.py

software -> celery:5.0.1 (singularity) kombu:5.0.2 py:3.8.3
            billiard:3.6.3.0 redis:3.5.3
platform -> system:Linux arch:64bit, ELF
            kernel version:5.4.0-48-generic imp:CPython
loader   -> celery.loaders.app.AppLoader
settings -> transport:redis results:disabled

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\nWhen NOT to use: Do not apply this fix if the logging behavior is intentionally designed to create multiple log files.\n\n

Why This Fix Works in Production

Trigger: - [x] I have included all related issues and possible duplicate issues
Mechanism: The `celery multi` command processes the `--logfile` parameter incorrectly, leading to unwanted log files
Why the fix works: Fixes the issue where `celery multi` creates unwanted log files by pre-formatting the logfile before detaching. (first fixed release: 5.0).

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 `celery multi` command processes the `--logfile` parameter incorrectly, leading to unwanted log files
Production symptom (often without a traceback): - [x] I have included all related issues and possible duplicate issues

Proof / Evidence

GitHub issue: #6426
Fix PR: https://github.com/celery/celery/pull/6488
First fixed release: 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: 0.59

Discussion

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

Jump to Sources Open on GitHub

“I haven't checked the code for it yet (and not so known with the celery code-base) but gave it some thought: Could it be that…”

@mfonville · 2020-10-21 · source

“@kwist-sgr @mfonville - If you have a moment to confirm the fix in #6488 works for you, it'd be appreciated”

@maybe-sybr · 2020-11-18 · source

“@maybe-sybr yes, this patch fixed the issue”

@kwist-sgr · 2020-11-18 · source

“@kwist-sgr - can you confirm for me that /tmp/celery was clean prior to running both commands? I assume that's the case and the extra empty…”

@maybe-sybr · 2020-11-17 · 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

software -> celery:5.0.1 (singularity) kombu:5.0.2 py:3.8.3
            billiard:3.6.3.0 redis:3.5.3
platform -> system:Linux arch:64bit, ELF
            kernel version:5.4.0-48-generic imp:CPython
loader   -> celery.loaders.app.AppLoader
settings -> transport:redis results:disabled

What Broke

Unwanted log files are created in the `/tmp/celery` directory, causing confusion and potential storage issues.

Why It Broke

The `celery multi` command processes the `--logfile` parameter incorrectly, leading to unwanted log files

Fix Options (Details)

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

pip install celery==5.0

When NOT to use: Do not apply this fix if the logging behavior is intentionally designed to create multiple log files.

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/6488

First fixed release: 5.0

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

When NOT to Use This Fix

Do not apply this fix if the logging behavior is intentionally designed to create multiple log files.

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
5.0	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 `celery multi`creates xxx_%I.log files (Fix)