urllib3 Towncrier version needs upgradation. (Fix)

The Fix

pip install urllib3==2.0.5

Based on closed urllib3/urllib3 issue #3099 · 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%.

Open PR/Commit

@@ -9,5 +9,5 @@ trustme==0.9.0
 cryptography==41.0.3;implementation_name!="pypy" or implementation_version>="7.3.10"
 backports.zoneinfo==0.2.1;python_version<"3.9"
-towncrier==21.9.0
+towncrier==23.6.0
 pytest-memray==1.4.0;python_version>="3.8" and python_version<"3.12" and sys_platform!="win32" and implementation_name=="cpython"

fix.md

Option A — Upgrade to fixed release\npip install urllib3==2.0.5\nWhen NOT to use: Do not use if it changes public behavior or if the failure cannot be reproduced.\n\n

Why This Fix Works in Production

Trigger: OpenSSL 1.1.1f 31 Mar 2020
Mechanism: The project was using an outdated Towncrier version that lacked new news fragment types
Why the fix works: Updated the Towncrier version from 21.9.0 to 23.6.0 to align with documentation and provide additional news fragment types. (first fixed release: 2.0.5).

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

Shows up under Python 3.8.10 in real deployments (not just unit tests).
The project was using an outdated Towncrier version that lacked new news fragment types
Production symptom (often without a traceback): OpenSSL 1.1.1f 31 Mar 2020

Proof / Evidence

GitHub issue: #3099
Fix PR: https://github.com/urllib3/urllib3/pull/3103
First fixed release: 2.0.5
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).

Jump to Sources Open on GitHub

“### Subject According to the doc at urllibs3/changelog/README.rst, link to the 5 default owncrier types points to the Towncrier version 23.6.1.dev0 where there are 6 types of news fragments available but in the dev-requirements.txt we insta”

Issue thread · issue description · source

Failure Signature (Search String)

OpenSSL 1.1.1f 31 Mar 2020
If we use any of the latest type of newsfragment, nox or towncrier fails to build CHANGELOG.rst

Copy-friendly signature

signature.txt

Failure Signature
-----------------
OpenSSL 1.1.1f  31 Mar 2020
If we use any of the latest type of newsfragment, nox or towncrier fails to build CHANGELOG.rst

Error Message

Signature-only (no traceback captured)

error.txt

Error Message
-------------
OpenSSL 1.1.1f  31 Mar 2020
If we use any of the latest type of newsfragment, nox or towncrier fails to build CHANGELOG.rst

Environment

Python: 3.8.10

Why It Broke

The project was using an outdated Towncrier version that lacked new news fragment types

Fix Options (Details)

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

pip install urllib3==2.0.5

When NOT to use: Do not use if it changes public behavior or if the failure cannot be reproduced.

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

Fix reference: https://github.com/urllib3/urllib3/pull/3103

First fixed release: 2.0.5

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

When NOT to Use This Fix

Do not use if it changes public behavior or if the failure cannot be reproduced.

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.
Add a TLS smoke test that performs a real handshake in CI (include CA bundle validation and hostname checks).
Alert on handshake failures by error string and endpoint to catch cert/CA changes quickly.

Version Compatibility Table

Version	Status
2.0.5	Fixed

Related Issues

No related fixes found.

Cluster: urllib3:configuration-error urllib3 hub urllib3 best practices All hubs All clusters

Related clusters: Data consistency SSL handshake Other

Sources

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