urllib3 `make test-gae` failed with "ImportError: No module

The Fix

pip install urllib3==1.25

Based on closed urllib3/urllib3 issue #974 · 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

@@ -49,6 +49,9 @@ test-all: requirements
 .PHONY: test-gae
 test-gae: requirements
+ifndef GAE_PYTHONPATH
+    $(error GAE_PYTHONPATH must be set)
+endif

repro.py

$ source venv/bin/activate 
$ make test-gae
...
GLOB sdist-make: /home/nori/src/urllib3/setup.py
gae inst-nodeps: /home/nori/src/urllib3/.tox/dist/urllib3-dev.zip
gae installed: backports.ssl-match-hostname==3.5.0.1,certifi==2016.8.31,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,pbr==1.10.0,pkginfo==1.3.2,pluggy==0.3.1,py==1.4.31,PySocks==1.5.6,requests==2.11.1,six==1.10.0,tornado==4.2.1,tox==2.1.1,twine==1.5.0,urllib3===dev,virtualenv==15.0.3
gae runtests: PYTHONHASHSEED='1616590051'
gae runtests: commands[0] | nosetests -c /home/nori/src/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 "/home/nori/src/urllib3/.tox/gae/lib/python2.7/site-packages/nose/core.py", line 121, in __init__
    **extra_args)
  File "/usr/lib64/python2.7/unittest/main.py", line 94, in __init__
    self.parseArgs(argv)
  File "/home/nori/src/urllib3/.tox/gae/lib/python2.7/site-packages/nose/core.py", line 145, in parseArgs
    self.config.configure(argv, doc=self.usage())
  File "/home/nori/src/urllib3/.tox/gae/lib/python2.7/site-packages/nose/config.py", line 346, in configure
    self.plugins.configure(options, self)
  File "/home/nori/src/urllib3/.tox/gae/lib/python2.7/site-packages/nose/plugins/manager.py", line 284, in configure
    cfg(options, config)
  File "/home/nori/src/urllib3/.tox/gae/lib/python2.7/site-packages/nose/plugins/manager.py", line 99, in __call__
    return self.call(*arg, **kw)
  File "/home/nori/src/urllib3/.tox/gae/lib/python2.7/site-packages/nose/plugins/manager.py", line 167, in simple
    result = meth(*arg, **kw)
  File "/home/nori/src/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: '/home/nori/src/urllib3/.tox/gae/bin/nosetests -c /home/nori/src/urllib3/test/appengine/nose.cfg test/appengine'
__________________________________________________________________________________________________________________________ summary ___________________________________________________________________________________________________________________________
ERROR:   gae: commands failed

verify

Re-run: source venv/bin/activate
Re-run: make test-gae

fix.md

Option A — Upgrade to fixed release\npip install urllib3==1.25\nWhen NOT to use: This fix is not applicable if the GAE_PYTHONPATH variable is intentionally unset for a reason.\n\n

Why This Fix Works in Production

Trigger: $ source venv/bin/activate
Mechanism: The GAE_PYTHONPATH environment variable was not set, causing an ImportError during tests
Why the fix works: Added a check in the Makefile to ensure that the GAE_PYTHONPATH environment variable is set before running the test-gae command. (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_PYTHONPATH environment variable was not set, causing an ImportError during tests
Surfaces as: $ source venv/bin/activate

Proof / Evidence

GitHub issue: #974
Fix PR: https://github.com/urllib3/urllib3/pull/975
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: 0.31

Discussion

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

Jump to Sources Open on GitHub

“The GAE_PYTHONPATH environment variable has to be set for nosegae to work. For example: Perhaps we could update the Makefile to warn / error if…”

@theacodes · 2016-09-10 · source

“That would be a good idea, I'd merge a patch that does that! =)”

@Lukasa · 2016-09-10 · source

“@jonparrott I set the variable but still have the problem. Should I install google appengine by myself?”

@eungjun-yi · 2016-09-10 · source

“I installed google appengine and now it works well. Thanks!”

@eungjun-yi · 2016-09-10 · source

Failure Signature (Search String)

$ source venv/bin/activate

Error Message

Stack trace

error.txt

Error Message
-------------
$ source venv/bin/activate 
$ make test-gae
...
GLOB sdist-make: /home/nori/src/urllib3/setup.py
gae inst-nodeps: /home/nori/src/urllib3/.tox/dist/urllib3-dev.zip
gae installed: backports.ssl-match-hostname==3.5.0.1,certifi==2016.8.31,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,pbr==1.10.0,pkginfo==1.3.2,pluggy==0.3.1,py==1.4.31,PySocks==1.5.6,requests==2.11.1,six==1.10.0,tornado==4.2.1,tox==2.1.1,twine==1.5.0,urllib3===dev,virtualenv==15.0.3
gae runtests: PYTHONHASHSEED='1616590051'
gae runtests: commands[0] | nosetests -c /home/nori/src/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 "/home/nori/src/urllib3/.tox/gae/lib/python2.7/site-packages/nose/core.py", line 121, in __init__
    **extra_args)
  File "/usr/lib64/python2.7/unittest/main.py", line 94, in __init__
    self.parseArgs(argv)
  File "/home/nori/src/urllib3/.tox/gae/lib/python2.7/site-packages/nose/core.py", line 145, in parseArgs
    self.config.configure(argv, doc=self.usage())
  File "/home/nori/src/urllib3/.tox/gae/lib/python2.7/site-packages/nose/config.py", line 346, in configure
    self.plugins.configure(options, self)
  File "/home/nori/src/urllib3/.tox/gae/lib/python2.7/site-packages/nose/plugins/manager.py", line 284, in configure
    cfg
... (truncated) ...

Minimal Reproduction

repro.py

$ source venv/bin/activate 
$ make test-gae
...
GLOB sdist-make: /home/nori/src/urllib3/setup.py
gae inst-nodeps: /home/nori/src/urllib3/.tox/dist/urllib3-dev.zip
gae installed: backports.ssl-match-hostname==3.5.0.1,certifi==2016.8.31,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,pbr==1.10.0,pkginfo==1.3.2,pluggy==0.3.1,py==1.4.31,PySocks==1.5.6,requests==2.11.1,six==1.10.0,tornado==4.2.1,tox==2.1.1,twine==1.5.0,urllib3===dev,virtualenv==15.0.3
gae runtests: PYTHONHASHSEED='1616590051'
gae runtests: commands[0] | nosetests -c /home/nori/src/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 "/home/nori/src/urllib3/.tox/gae/lib/python2.7/site-packages/nose/core.py", line 121, in __init__
    **extra_args)
  File "/usr/lib64/python2.7/unittest/main.py", line 94, in __init__
    self.parseArgs(argv)
  File "/home/nori/src/urllib3/.tox/gae/lib/python2.7/site-packages/nose/core.py", line 145, in parseArgs
    self.config.configure(argv, doc=self.usage())
  File "/home/nori/src/urllib3/.tox/gae/lib/python2.7/site-packages/nose/config.py", line 346, in configure
    self.plugins.configure(options, self)
  File "/home/nori/src/urllib3/.tox/gae/lib/python2.7/site-packages/nose/plugins/manager.py", line 284, in configure
    cfg(options, config)
  File "/home/nori/src/urllib3/.tox/gae/lib/python2.7/site-packages/nose/plugins/manager.py", line 99, in __call__
    return self.call(*arg, **kw)
  File "/home/nori/src/urllib3/.tox/gae/lib/python2.7/site-packages/nose/plugins/manager.py", line 167, in simple
    result = meth(*arg, **kw)
  File "/home/nori/src/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: '/home/nori/src/urllib3/.tox/gae/bin/nosetests -c /home/nori/src/urllib3/test/appengine/nose.cfg test/appengine'
__________________________________________________________________________________________________________________________ summary ___________________________________________________________________________________________________________________________
ERROR:   gae: commands failed

Environment

Python: 2.7

What Broke

Running `make test-gae` resulted in an ImportError, preventing tests from executing.

Why It Broke

The GAE_PYTHONPATH environment variable was not set, causing an ImportError during tests

Fix Options (Details)

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

pip install urllib3==1.25

When NOT to use: This fix is not applicable if the GAE_PYTHONPATH variable is intentionally unset for a reason.

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/975

First fixed release: 1.25

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

When NOT to Use This Fix

This fix is not applicable if the GAE_PYTHONPATH variable is intentionally unset for a reason.

Verify Fix

verify

Re-run: source venv/bin/activate
Re-run: make test-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

Version	Status
1.25	Fixed

Related Issues

No related fixes found.

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Related clusters: Data consistency SSL handshake Other

Sources

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

urllib3 `make test-gae` failed with "ImportError: No module named dev_appserver" (Fix)