The Fix
pip install urllib3==1.26.7
Based on closed urllib3/urllib3 issue #2313 · 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%.
@@ -201,15 +201,17 @@ def _new_conn(self) -> socket.socket:
)
except socket.gaierror as e:
- raise NameResolutionError(self.host, self, e)
- except SocketTimeout:
+ raise NameResolutionError(self.host, self, e) from e
... SocketTimeout stacktrace ...
During handling of the above exception, another exception occurred:
... ReadTimeoutError stacktrace ...
Re-run the minimal reproduction on your broken version, then apply the fix and re-run.
Option A — Upgrade to fixed release\npip install urllib3==1.26.7\nWhen NOT to use: This fix should not be used if the original exception context is required for debugging.\n\n
Why This Fix Works in Production
- Trigger: [v2] Chaining exceptions
- Mechanism: Implicit exception handling in urllib3 was misleading due to lack of explicit chaining
- Why the fix works: Explicitly chains exceptions in urllib3 to improve error messages and clarity for users. (first fixed release: 1.26.7).
- 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
- Implicit exception handling in urllib3 was misleading due to lack of explicit chaining
- Production symptom (often without a traceback): [v2] Chaining exceptions
Proof / Evidence
- GitHub issue: #2313
- Fix PR: https://github.com/urllib3/urllib3/pull/2340
- First fixed release: 1.26.7
- Reproduced locally: No (not executed)
- Last verified: 2026-02-09
- Confidence: 0.95
- Did this fix it?: Yes (upstream fix exists)
- Own content ratio: 0.72
Discussion
High-signal excerpts from the issue thread (symptoms, repros, edge-cases).
“Thanks for opening this! Let's move towards the explicit chaining if only for the better message. This work will also expose places where maybe we…”
Failure Signature (Search String)
- [v2] Chaining exceptions
- Currently urllib3 doesn't chain exceptions explicitly when wrapping exceptions (this feature wasn't available in Python 2 AFAIK). For example:
Copy-friendly signature
Failure Signature
-----------------
[v2] Chaining exceptions
Currently urllib3 doesn't chain exceptions explicitly when wrapping exceptions (this feature wasn't available in Python 2 AFAIK). For example:
Error Message
Signature-only (no traceback captured)
Error Message
-------------
[v2] Chaining exceptions
Currently urllib3 doesn't chain exceptions explicitly when wrapping exceptions (this feature wasn't available in Python 2 AFAIK). For example:
Minimal Reproduction
... SocketTimeout stacktrace ...
During handling of the above exception, another exception occurred:
... ReadTimeoutError stacktrace ...
What Broke
Users received confusing error messages when exceptions were raised.
Why It Broke
Implicit exception handling in urllib3 was misleading due to lack of explicit chaining
Fix Options (Details)
Option A — Upgrade to fixed release Safe default (recommended)
pip install urllib3==1.26.7
Use when you can deploy the upstream fix. It is usually lower-risk than long-lived workarounds.
Option D — Guard side-effects with OnceOnly Guardrail for side-effects
Mitigate duplicate external side-effects under retries/timeouts/agent loops by gating the operation before calling external systems.
- Place OnceOnly between your code/agent and real side-effects (Stripe, emails, CRM, APIs).
- Use a stable key per side-effect (e.g., customer_id + action + idempotency_key).
- Fail-safe: configure fail-open vs fail-closed based on blast radius and spend risk.
Show example snippet (optional)
from onceonly import OnceOnly
import os
once = OnceOnly(api_key=os.environ["ONCEONLY_API_KEY"], fail_open=True)
# Stable idempotency key per real side-effect.
# Use a request id / job id / webhook delivery id / Stripe event id, etc.
event_id = "evt_..." # replace
key = f"stripe:webhook:{event_id}"
res = once.check_lock(key=key, ttl=3600)
if res.duplicate:
return {"status": "already_processed"}
# Safe to execute the side-effect exactly once.
handle_event(event_id)
Fix reference: https://github.com/urllib3/urllib3/pull/2340
First fixed release: 1.26.7
Last verified: 2026-02-09. Validate in your environment.
When NOT to Use This Fix
- This fix should not be used if the original exception context is required for debugging.
- Do not use this to hide logic bugs or data corruption. Use it to block duplicate external side-effects and enforce tool permissions/spend caps.
Verify Fix
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
- Add a CI check that diffs key outputs after upgrades (OpenAPI schema snapshots, JSON payload shapes, CLI output).
- Upgrade behind a canary and run integration tests against the canary before 100% rollout.
- 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 |
|---|---|
| 1.26.7 | Fixed |
Related Issues
No related fixes found.
Sources
We don’t republish the full GitHub discussion text. Use the links above for context.