The Fix
pip install urllib3==1.25
Based on closed urllib3/urllib3 issue #695 · 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%.
@@ -71,6 +71,12 @@
}
+if hasattr(ssl, 'PROTOCOL_TLSv1_1') and hasattr(OpenSSL.SSL, 'TLSv1_1_METHOD'):
+ _openssl_versions[ssl.PROTOCOL_TLSv1_1] = OpenSSL.SSL.TLSv1_1_METHOD
+
Option A — Upgrade to fixed release\npip install urllib3==1.25\nWhen NOT to use: Do not use this fix if your application requires support for older SSL protocols only.\n\n
Why This Fix Works in Production
- Trigger: PyOpenSSL support doesn't work with TLSv1.1 and TLSv1.2
- Mechanism: Adds support for TLSv1.1 and TLSv1.2 in pyOpenSSL, addressing the issue where urllib3.contrib.pyopenssl only supported older protocols.
- Why the fix works: Adds support for TLSv1.1 and TLSv1.2 in pyOpenSSL, addressing the issue where urllib3.contrib.pyopenssl only supported older protocols. (first fixed release: 1.25).
- 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): PyOpenSSL support doesn't work with TLSv1.1 and TLSv1.2
Proof / Evidence
- GitHub issue: #695
- Fix PR: https://github.com/urllib3/urllib3/pull/696
- First fixed release: 1.25
- Reproduced locally: No (not executed)
- Last verified: 2026-02-09
- Confidence: 0.85
- Did this fix it?: Yes (upstream fix exists)
- Own content ratio: 0.71
Discussion
High-signal excerpts from the issue thread (symptoms, repros, edge-cases).
“To be clear this should be an extremely simple fix: conditionally attempt to use the TLSv1_1 and TLSv1_2 names, and if they exist then add…”
“+1, @itamarst would you like to do a PR for this?”
“Might have a few free minutes at work tomorrow, maybe.”
Failure Signature (Search String)
- PyOpenSSL support doesn't work with TLSv1.1 and TLSv1.2
- `docker-py` tries to use latest protocol version in the ssl module, so use ssl.PROTOCOL_TLSv1_2. Unfortunately urllib3.contrib.pyopenssl only has SSLv2_3 and TLSv1 so it breaks:
Copy-friendly signature
Failure Signature
-----------------
PyOpenSSL support doesn't work with TLSv1.1 and TLSv1.2
`docker-py` tries to use latest protocol version in the ssl module, so use ssl.PROTOCOL_TLSv1_2. Unfortunately urllib3.contrib.pyopenssl only has SSLv2_3 and TLSv1 so it breaks:
Error Message
Signature-only (no traceback captured)
Error Message
-------------
PyOpenSSL support doesn't work with TLSv1.1 and TLSv1.2
`docker-py` tries to use latest protocol version in the ssl module, so use ssl.PROTOCOL_TLSv1_2. Unfortunately urllib3.contrib.pyopenssl only has SSLv2_3 and TLSv1 so it breaks:
Fix Options (Details)
Option A — Upgrade to fixed release Safe default (recommended)
pip install urllib3==1.25
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/696
First fixed release: 1.25
Last verified: 2026-02-09. Validate in your environment.
When NOT to Use This Fix
- Do not use this fix if your application requires support for older SSL protocols only.
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 |
|---|---|
| 1.25 | Fixed |
Related Issues
No related fixes found.
Sources
We don’t republish the full GitHub discussion text. Use the links above for context.