redis-py max_connections is not being honoured in

The Fix

pip install redis==7.1.0

Based on closed redis/redis-py issue #3684 · 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

@@ -20,6 +20,7 @@
     InvalidPipelineStack,
     InvalidResponse,
+    MaxConnectionsError,
     OutOfMemoryError,
     PubSubError,

repro.py

def make_connection(self) -> "ConnectionInterface":
    if self._created_connections >= self.max_connections:
        raise ConnectionError("Too many connections")
    self._created_connections += 1
And in the reconnection logic:

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 redis==7.1.0\nWhen NOT to use: This fix is not suitable if existing error handling relies on the generic ConnectionError.\n\n

Why This Fix Works in Production

Trigger: Error handling of execute_command
Mechanism: The ConnectionError raised when exceeding max_connections leads to unnecessary cluster reinitialization
Why the fix works: Addresses issue #3684 by introducing a more specific MaxConnectionsError exception that is raised when a connection pool reaches its maximum connections limit. (first fixed release: 7.1.0).

Production impact:

If left unfixed, retry loops can amplify load and turn a small outage into a cascade (thundering herd).

Why This Breaks in Prod

The ConnectionError raised when exceeding max_connections leads to unnecessary cluster reinitialization
Surfaces as: Error handling of execute_command

Proof / Evidence

GitHub issue: #3684
Fix PR: https://github.com/redis/redis-py/pull/3698
First fixed release: 7.1.0
Reproduced locally: No (not executed)
Last verified: 2026-02-08
Confidence: 0.75
Did this fix it?: Yes (upstream fix exists)
Own content ratio: 0.75

Discussion

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

Jump to Sources Open on GitHub

“Hi @Sakin-Subbaiah, Thanks for reporting this! It looks like an interesting issue to tackle — I’m looking forward to working on a fix. 🙂”

@petyaslavova · 2025-06-27 · source

“Hi @petyaslavova, thanks for looking into this. Do you have any ETA for this?”

@Sakin-Subbaiah · 2025-07-01 · source

“Thanks @petyaslavova for the review, we have raised a PR https://github.com/redis/redis-py/pull/3698 using MaxConnectionError https://github.com/redis/redis-py/blob/a757bad78bf18869cdceb370ca8d05d3a7c96942/redis/exceptions.py#L223 as we observed it was present”

@ns-ssubbaiah · 2025-07-16 · source

“> ch as MaxConnectionLimitError(subclass of Exception) instead of ConnectionError help in this scenario? Hi @ns-ssubbaiah, I think that the approach with an error that is…”

@petyaslavova · 2025-07-16 · source

Failure Signature (Search String)

Error handling of execute_command

Error Message

Stack trace

error.txt

Error Message
-------------
Error handling of execute_command

Minimal Reproduction

repro.py

def make_connection(self) -> "ConnectionInterface":
    if self._created_connections >= self.max_connections:
        raise ConnectionError("Too many connections")
    self._created_connections += 1
And in the reconnection logic:

What Broke

Exceeding max_connections causes connection pool exhaustion and repeated connection attempts.

Why It Broke

The ConnectionError raised when exceeding max_connections leads to unnecessary cluster reinitialization

Fix Options (Details)

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

pip install redis==7.1.0

When NOT to use: This fix is not suitable if existing error handling relies on the generic ConnectionError.

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

Fix reference: https://github.com/redis/redis-py/pull/3698

First fixed release: 7.1.0

Last verified: 2026-02-08. Validate in your environment.

When NOT to Use This Fix

This fix is not suitable if existing error handling relies on the generic ConnectionError.

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
7.1.0	Fixed

Related Issues

No related fixes found.

Cluster: redis-py:retry-storm redis-py hub redis-py best practices All hubs All clusters

Related clusters: Configuration error Data consistency Race condition

Sources

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

redis-py max_connections is not being honoured in RedisCluster mode (Fix)