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urllib3 Running `tox -e gae` is broken on current master (Fix)

Fixed
Spec
Package
urllib3
Fixed In
1.25
Python
2.7
Verdict
Status
Fixed
Safe for prod
Yes
Risk
Low
Last verified
2026-02-09
Own content ratio
0.29
#1183 ai caching llm tls Updated: 2026-02-13
Issue #1183

The Fix

pip install urllib3==1.25

Based on closed urllib3/urllib3 issue #1183 · 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%.

Jump to Verify Open PR/Commit
@@ -1,108 +0,0 @@ @@ -1,108 +0,0 @@ -#!/usr/bin/env python - -# Copyright 2015 Google Inc. All rights reserved.
repro.py
$ tox -e gae GLOB sdist-make: /Users/alexwlchan/repos/urllib3/setup.py gae inst-nodeps: /Users/alexwlchan/repos/urllib3/.tox/dist/urllib3-dev.zip gae installed: appdirs==1.4.3,backports.ssl-match-hostname==3.5.0.1,certifi==2017.4.17,coverage==3.7.1,funcsigs==1.0.2,mock==1.3.0,nose==1.3.7,nose-exclude==0.4.1,NoseGAE==0.5.7,packaging==16.8,pbr==3.0.1,pkginfo==1.4.1,pluggy==0.3.1,psutil==4.3.1,py==1.4.33,pyparsing==2.2.0,PySocks==1.5.6,pytest==3.1.0,requests==2.14.2,six==1.10.0,tornado==4.2.1,tox==2.1.1,twine==1.5.0,urllib3===dev,virtualenv==15.1.0 gae runtests: PYTHONHASHSEED='2409600760' gae runtests: commands[0] | nosetests -c /Users/alexwlchan/repos/urllib3/test/appengine/nose.cfg test/appengine Traceback (most recent call last): File ".tox/gae/bin/nosetests", line 11, in <module> sys.exit(run_exit()) File "/Users/alexwlchan/repos/urllib3/.tox/gae/lib/python2.7/site-packages/nose/core.py", line 121, in __init__ **extra_args) File "/usr/local/Cellar/python/2.7.13/Frameworks/Python.framework/Versions/2.7/lib/python2.7/unittest/main.py", line 94, in __init__ self.parseArgs(argv) File "/Users/alexwlchan/repos/urllib3/.tox/gae/lib/python2.7/site-packages/nose/core.py", line 145, in parseArgs self.config.configure(argv, doc=self.usage()) File "/Users/alexwlchan/repos/urllib3/.tox/gae/lib/python2.7/site-packages/nose/config.py", line 346, in configure self.plugins.configure(options, self) File "/Users/alexwlchan/repos/urllib3/.tox/gae/lib/python2.7/site-packages/nose/plugins/manager.py", line 284, in configure cfg(options, config) File "/Users/alexwlchan/repos/urllib3/.tox/gae/lib/python2.7/site-packages/nose/plugins/manager.py", line 99, in __call__ return self.call(*arg, **kw) File "/Users/alexwlchan/repos/urllib3/.tox/gae/lib/python2.7/site-packages/nose/plugins/manager.py", line 167, in simple result = meth(*arg, **kw) File "/Users/alexwlchan/repos/urllib3/.tox/gae/lib/python2.7/site-packages/nosegae.py", line 91, in configure import dev_appserver ImportError: No module named dev_appserver ERROR: InvocationError: '/Users/alexwlchan/repos/urllib3/.tox/gae/bin/nosetests -c /Users/alexwlchan/repos/urllib3/test/appengine/nose.cfg test/appengine' ________________________________________________________________________________ summary _________________________________________________________________________________ ERROR: gae: commands failed
verify
Re-run: tox -e gae
fix.md
Option A — Upgrade to fixed release\npip install urllib3==1.25\nWhen NOT to use: This fix should not be applied if the environment does not require GAE support.\n\n

Why This Fix Works in Production

  • Trigger: $ tox -e gae
  • Mechanism: The GAE build fails due to a missing dev_appserver module during test execution
  • Why the fix works: Fixes the GAE build by using gcp-devrel's script for fetching the app engine SDK and updating the version of NoseGAE. (first fixed release: 1.25).
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 2.7 in real deployments (not just unit tests).
  • The GAE build fails due to a missing dev_appserver module during test execution
  • Surfaces as: $ tox -e gae

Proof / Evidence

  • GitHub issue: #1183
  • Fix PR: https://github.com/urllib3/urllib3/pull/1186
  • First fixed release: 1.25
  • Reproduced locally: No (not executed)
  • Last verified: 2026-02-09
  • Confidence: 0.95
  • Did this fix it?: Yes (upstream fix exists)
  • Own content ratio: 0.29

Discussion

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

Jump to Sources Open on GitHub
“@alexwlchan yes, sending a PR to fix shortly.”
@theacodes · 2017-05-28 · source
“Hmm. I found the most recent successful Travis job, and pinned based on the requirements reported by tox: Same issue.”
@alexwlchan · 2017-05-28 · source
“Interesting, this passes on Travis, with a matching set of versions – see https://travis-ci.org/shazow/urllib3/jobs/236925046 – but not on my local machine.”
@alexwlchan · 2017-05-28 · source
“But it doesn’t pass in Travis on my fork – https://travis-ci.org/alexwlchan/urllib3/jobs/236924925 – I wonder, is there something dodgy about the Travis cache for urllib3 that’s…”
@alexwlchan · 2017-05-28 · source

Failure Signature (Search String)

  • $ tox -e gae

Error Message

Stack trace
error.txt
Error Message ------------- $ tox -e gae GLOB sdist-make: /Users/alexwlchan/repos/urllib3/setup.py gae inst-nodeps: /Users/alexwlchan/repos/urllib3/.tox/dist/urllib3-dev.zip gae installed: appdirs==1.4.3,backports.ssl-match-hostname==3.5.0.1,certifi==2017.4.17,coverage==3.7.1,funcsigs==1.0.2,mock==1.3.0,nose==1.3.7,nose-exclude==0.4.1,NoseGAE==0.5.7,packaging==16.8,pbr==3.0.1,pkginfo==1.4.1,pluggy==0.3.1,psutil==4.3.1,py==1.4.33,pyparsing==2.2.0,PySocks==1.5.6,pytest==3.1.0,requests==2.14.2,six==1.10.0,tornado==4.2.1,tox==2.1.1,twine==1.5.0,urllib3===dev,virtualenv==15.1.0 gae runtests: PYTHONHASHSEED='2409600760' gae runtests: commands[0] | nosetests -c /Users/alexwlchan/repos/urllib3/test/appengine/nose.cfg test/appengine Traceback (most recent call last): File ".tox/gae/bin/nosetests", line 11, in <module> sys.exit(run_exit()) File "/Users/alexwlchan/repos/urllib3/.tox/gae/lib/python2.7/site-packages/nose/core.py", line 121, in __init__ **extra_args) File "/usr/local/Cellar/python/2.7.13/Frameworks/Python.framework/Versions/2.7/lib/python2.7/unittest/main.py", line 94, in __init__ self.parseArgs(argv) File "/Users/alexwlchan/repos/urllib3/.tox/gae/lib/python2.7/site-packages/nose/core.py", line 145, in parseArgs self.config.configure(argv, doc=self.usage()) File "/Users/alexwlchan/repos/urllib3/.tox/gae/lib/python2.7/site-packages/nose/config.py", line 346, in configure se ... (truncated) ...

Minimal Reproduction

repro.py
$ tox -e gae GLOB sdist-make: /Users/alexwlchan/repos/urllib3/setup.py gae inst-nodeps: /Users/alexwlchan/repos/urllib3/.tox/dist/urllib3-dev.zip gae installed: appdirs==1.4.3,backports.ssl-match-hostname==3.5.0.1,certifi==2017.4.17,coverage==3.7.1,funcsigs==1.0.2,mock==1.3.0,nose==1.3.7,nose-exclude==0.4.1,NoseGAE==0.5.7,packaging==16.8,pbr==3.0.1,pkginfo==1.4.1,pluggy==0.3.1,psutil==4.3.1,py==1.4.33,pyparsing==2.2.0,PySocks==1.5.6,pytest==3.1.0,requests==2.14.2,six==1.10.0,tornado==4.2.1,tox==2.1.1,twine==1.5.0,urllib3===dev,virtualenv==15.1.0 gae runtests: PYTHONHASHSEED='2409600760' gae runtests: commands[0] | nosetests -c /Users/alexwlchan/repos/urllib3/test/appengine/nose.cfg test/appengine Traceback (most recent call last): File ".tox/gae/bin/nosetests", line 11, in <module> sys.exit(run_exit()) File "/Users/alexwlchan/repos/urllib3/.tox/gae/lib/python2.7/site-packages/nose/core.py", line 121, in __init__ **extra_args) File "/usr/local/Cellar/python/2.7.13/Frameworks/Python.framework/Versions/2.7/lib/python2.7/unittest/main.py", line 94, in __init__ self.parseArgs(argv) File "/Users/alexwlchan/repos/urllib3/.tox/gae/lib/python2.7/site-packages/nose/core.py", line 145, in parseArgs self.config.configure(argv, doc=self.usage()) File "/Users/alexwlchan/repos/urllib3/.tox/gae/lib/python2.7/site-packages/nose/config.py", line 346, in configure self.plugins.configure(options, self) File "/Users/alexwlchan/repos/urllib3/.tox/gae/lib/python2.7/site-packages/nose/plugins/manager.py", line 284, in configure cfg(options, config) File "/Users/alexwlchan/repos/urllib3/.tox/gae/lib/python2.7/site-packages/nose/plugins/manager.py", line 99, in __call__ return self.call(*arg, **kw) File "/Users/alexwlchan/repos/urllib3/.tox/gae/lib/python2.7/site-packages/nose/plugins/manager.py", line 167, in simple result = meth(*arg, **kw) File "/Users/alexwlchan/repos/urllib3/.tox/gae/lib/python2.7/site-packages/nosegae.py", line 91, in configure import dev_appserver ImportError: No module named dev_appserver ERROR: InvocationError: '/Users/alexwlchan/repos/urllib3/.tox/gae/bin/nosetests -c /Users/alexwlchan/repos/urllib3/test/appengine/nose.cfg test/appengine' ________________________________________________________________________________ summary _________________________________________________________________________________ ERROR: gae: commands failed

Environment

  • Python: 2.7

What Broke

Running tests with tox for GAE results in an ImportError, preventing successful test execution.

Why It Broke

The GAE build fails due to a missing dev_appserver module during test execution

Fix Options (Details)

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

pip install urllib3==1.25

When NOT to use: This fix should not be applied if the environment does not require GAE support.

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/1186

First fixed release: 1.25

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

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When NOT to Use This Fix

  • This fix should not be applied if the environment does not require GAE support.

Verify Fix

verify
Re-run: tox -e gae

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

VersionStatus
1.25 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.

Source & Disclaimer: Analysis derived from GitHub Issue #1183. Not affiliated with the library maintainers. Verify before production use.