urllib3 Allow building with setuptools-scm >= 9 (Fix)

The Fix

pip install urllib3==2.6.0

Based on closed urllib3/urllib3 issue #3652 · 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.

Open PR/Commit

@@ -0,0 +1 @@
@@ -0,0 +1 @@
+Allowed building the urllib3 package with newer setuptools-scm v9.x.
diff --git a/pyproject.toml b/pyproject.toml
index 99856c0bd9..dd2600be4f 100644

fix.md

Option A — Upgrade to fixed release\npip install urllib3==2.6.0\nWhen NOT to use: This fix is not applicable if using setuptools-scm versions below 9.\n\n

Why This Fix Works in Production

Trigger: Users were unable to build the urllib3 package with newer setuptools-scm versions.
Mechanism: Updated the upper limit for setuptools-scm in pyproject.toml to allow version 9.x.
Why the fix works: Updated the upper limit for setuptools-scm in pyproject.toml to allow version 9.x. (first fixed release: 2.6.0).

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

Production symptom (often without a traceback): Users were unable to build the urllib3 package with newer setuptools-scm versions.

Proof / Evidence

GitHub issue: #3652
Fix PR: https://github.com/urllib3/urllib3/pull/3682
First fixed release: 2.6.0
Reproduced locally: No (not executed)
Last verified: 2026-02-09
Confidence: 0.85
Did this fix it?: Yes (upstream fix exists)
Own content ratio: 0.74

Discussion

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

Jump to Sources Open on GitHub

“All 9.x releases of setuptools-scm have been yanked on PyPI, we'll need to wait for some time <img width="1920" height="1200" alt="Release history of setuptools-scm on…”

@illia-v · 2025-08-14 · source

“It looks like there's a valid 9.2.0 version there now: https://pypi.org/project/setuptools-scm/9.2.0/#history Should I submit a patch to remove the <9 restriction?”

@threexc · 2025-09-22 · source

Failure Signature (Search String)

Users were unable to build the urllib3 package with newer setuptools-scm versions.

Copy-friendly signature

signature.txt

Failure Signature
-----------------
Users were unable to build the urllib3 package with newer setuptools-scm versions.

Error Message

Signature-only (no traceback captured)

error.txt

Error Message
-------------
Users were unable to build the urllib3 package with newer setuptools-scm versions.

What Broke

Users were unable to build the urllib3 package with newer setuptools-scm versions.

Fix Options (Details)

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

pip install urllib3==2.6.0

When NOT to use: This fix is not applicable if using setuptools-scm versions below 9.

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/3682

First fixed release: 2.6.0

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

When NOT to Use This Fix

This fix is not applicable if using setuptools-scm versions below 9.

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.

Version Compatibility Table

Version	Status
2.6.0	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

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