Celery RedisBackend does not retry on store

The Fix

pip install celery==5.5.0

Based on closed celery/celery issue #9613 · 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

@@ -359,6 +359,11 @@ def _params_from_url(self, url, defaults):
         return connparams
 
+    def exception_safe_to_retry(self, exc):
+        if isinstance(exc, self.connection_errors):
+            return True

repro.py

try:
    from redis import exceptions
except ImportError:
    exceptions = None

class test_RedisBackend(basetest_RedisBackend):
    def test_store_result_with_retries(self):
        self.app.conf.result_backend_always_retry, prev = True, self.app.conf.result_backend_always_retry

        try:
            b = self.Backend(app=self.app)
            # b.exception_safe_to_retry = lambda exc: True
            b._sleep = Mock()
            b._get_task_meta_for = Mock()
            b._get_task_meta_for.return_value = {
                'status': states.RETRY,
                'result': {
                    "exc_type": "Exception",
                    "exc_message": ["failed"],
                    "exc_module": "builtins",
                },
            }
            b._store_result = Mock()
            b._store_result.side_effect = [
                exceptions.ConnectionError("failed"),
                42
            ]
            res = b.store_result("testing", 42, states.SUCCESS)   # raises redis.exceptions.ConnectionError: failed
            assert res == 42
            assert b._sleep.call_count == 1
        finally:
            self.app.conf.result_backend_always_retry = prev

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 behavior of result_backend_always_retry is not intended to change.\n\n

Why This Fix Works in Production

Trigger: RedisBackend does not retry on store_result even with result_backend_always_retry=True
Mechanism: The exception_safe_to_retry method was not defined for RedisBackend, preventing retries on store_result
Why the fix works: Defines the exception_safe_to_retry method for RedisBackend to ensure that operations like store_result retry correctly when result_backend_always_retry is set to True. (first fixed release: 5.5.0).

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

Triggered by an upgrade/regression window: 1.1–2.4.0 breaks; 5.5.0 is the first fixed release.
The exception_safe_to_retry method was not defined for RedisBackend, preventing retries on store_result
Production symptom (often without a traceback): RedisBackend does not retry on store_result even with result_backend_always_retry=True

Proof / Evidence

GitHub issue: #9613
Fix PR: https://github.com/celery/celery/pull/9614
First fixed release: 5.5.0
Affected versions: 1.1–2.4.0
Reproduced locally: No (not executed)
Last verified: 2026-02-09
Confidence: 0.85
Did this fix it?: Yes (upstream fix exists)
Own content ratio: 0.48

Discussion

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

Jump to Sources Open on GitHub

“ # Checklist  - [x] I hav”

Issue thread · issue description · source

Failure Signature (Search String)

RedisBackend does not retry on store_result even with result_backend_always_retry=True
- [x] I have included all related issues and possible duplicate issues

Copy-friendly signature

signature.txt

Failure Signature
-----------------
RedisBackend does not retry on store_result even with result_backend_always_retry=True
- [x] I have included all related issues and possible duplicate issues

Error Message

Signature-only (no traceback captured)

error.txt

Error Message
-------------
RedisBackend does not retry on store_result even with result_backend_always_retry=True
- [x] I have included all related issues and possible duplicate issues

Minimal Reproduction

repro.py

try:
    from redis import exceptions
except ImportError:
    exceptions = None

class test_RedisBackend(basetest_RedisBackend):
    def test_store_result_with_retries(self):
        self.app.conf.result_backend_always_retry, prev = True, self.app.conf.result_backend_always_retry

        try:
            b = self.Backend(app=self.app)
            # b.exception_safe_to_retry = lambda exc: True
            b._sleep = Mock()
            b._get_task_meta_for = Mock()
            b._get_task_meta_for.return_value = {
                'status': states.RETRY,
                'result': {
                    "exc_type": "Exception",
                    "exc_message": ["failed"],
                    "exc_module": "builtins",
                },
            }
            b._store_result = Mock()
            b._store_result.side_effect = [
                exceptions.ConnectionError("failed"),
                42
            ]
            res = b.store_result("testing", 42, states.SUCCESS)   # raises redis.exceptions.ConnectionError: failed
            assert res == 42
            assert b._sleep.call_count == 1
        finally:
            self.app.conf.result_backend_always_retry = prev

What Broke

Operations like store_result fail without retrying, causing potential data loss.

Why It Broke

The exception_safe_to_retry method was not defined for RedisBackend, preventing retries on store_result

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 behavior of result_backend_always_retry is not intended to change.

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/9614

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 behavior of result_backend_always_retry is not intended to change.

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
1.1	Broken
2.4.0	Broken
5.5.0	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 RedisBackend does not retry on store_result even with result_backend_always_retry=True (Fix)