Celery Bug in `revoke_by_stamped_headers` when no current

The Fix

pip install celery==5.5.0

Based on closed celery/celery issue #9446 · PR/commit linked

Production note: Watch p95/p99 latency and retry volume; timeouts can turn into retry storms and duplicate side-effects.

Jump to Verify Open PR/Commit

@@ -527,7 +527,8 @@ def revoke_by_stamped_headers(self, headers, destination=None, terminate=False,
             for host in result:
                 for response in host.values():
-                    task_ids.update(response['ok'])
+                    if isinstance(response['ok'], set):
+                        task_ids.update(response['ok'])

repro.py

app.control.revoke_by_stamped_headers(
        {"myheader": ["myvalue"]},
        terminate=False,
        reply=True,
        timeout=5,
    )

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==5.5.0\nWhen NOT to use: Do not use this fix if the revoke method needs to handle multiple headers differently.\n\n

Why This Fix Works in Production

Trigger: Invalid task IDs were revoked, leading to gibberish responses from the method call.
Mechanism: The method attempted to revoke invalid task IDs when no current worker tasks matched the header
Why the fix works: Fixed a bug in `revoke_by_stamped_headers` that caused invalid task IDs to be revoked when no current worker tasks matched the header. (first fixed release: 5.5.0).

Production impact:

If left unfixed, this can cause silent data inconsistencies that propagate (bad cache entries, incorrect downstream decisions).

Why This Breaks in Prod

The method attempted to revoke invalid task IDs when no current worker tasks matched the header
Production symptom (often without a traceback): Invalid task IDs were revoked, leading to gibberish responses from the method call.

Proof / Evidence

GitHub issue: #9446
Fix PR: https://github.com/celery/celery/pull/9575
First fixed release: 5.5.0
Reproduced locally: No (not executed)
Last verified: 2026-02-09
Confidence: 0.95
Did this fix it?: Yes (upstream fix exists)
Own content ratio: 0.67

Discussion

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

Jump to Sources Open on GitHub

“These lines here: https://github.com/celery/celery/blob/e3eaa675ee1e48d03a018f0abe763cc1dfb380a5/celery/app/control.py#L527-L530 are problematic, because host.values() contains something like {'ok': "headers {'myheader': ['myvalue']} flagge”

Issue thread · issue description · source

Failure Signature (Search String)

Invalid task IDs were revoked, leading to gibberish responses from the method call.

Copy-friendly signature

signature.txt

Failure Signature
-----------------
Invalid task IDs were revoked, leading to gibberish responses from the method call.

Error Message

Signature-only (no traceback captured)

error.txt

Error Message
-------------
Invalid task IDs were revoked, leading to gibberish responses from the method call.

Minimal Reproduction

repro.py

app.control.revoke_by_stamped_headers(
        {"myheader": ["myvalue"]},
        terminate=False,
        reply=True,
        timeout=5,
    )

What Broke

Invalid task IDs were revoked, leading to gibberish responses from the method call.

Why It Broke

The method attempted to revoke invalid task IDs when no current worker tasks matched the header

Fix Options (Details)

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

pip install celery==5.5.0

When NOT to use: Do not use this fix if the revoke method needs to handle multiple headers differently.

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/9575

First fixed release: 5.5.0

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

When NOT to Use This Fix

Do not use this fix if the revoke method needs to handle multiple headers differently.

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

Make timeouts explicit and test them (unit + integration) to avoid silent behavior changes.
Instrument retries (attempt count + reason) and alert on spikes to catch dependency slowdowns.

Version Compatibility Table

Version	Status
5.5.0	Fixed

Related Issues

No related fixes found.

Cluster: celery:data-consistency Celery hub Celery best practices All hubs All clusters

Related clusters: Configuration error Duplicates Duplicate processing

Sources

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

Celery Bug in `revoke_by_stamped_headers` when no current worker tasks match the header (Fix)