Fix AttributeError: 'ClientConnectorCertificateError' object has no attribute '_os_error'. by themylogin · Pull Request #12136 · aio-libs/aiohttp

themylogin · 2026-02-23T14:20:03Z

What do these changes do?

ClientConnectorCertificateError is a subclass of ClientConnectorError and should have all of its attributes (Liskov substitution principle). However, when I try to access the os_error attribute in my exception handler, I get the following exception:

AttributeError: 'ClientConnectorCertificateError' object has no attribute '_os_error'.

Are there changes in behavior for the user?

Users that use hasattr(e, 'os_error') to ensure that e is not an instance of ClientConnectorCertificateError (or its subclasses), will have their code broken.

Is it a substantial burden for the maintainers to support this?

There should be none.

Checklist

I think the code is well written
Unit tests for the changes exist
Documentation reflects the changes
If you provide code modification, please add yourself to CONTRIBUTORS.txt
- The format is <Name> <Surname>.
- Please keep alphabetical order, the file is sorted by names.
Add a new news fragment into the CHANGES/ folder
- name it <issue_or_pr_num>.<type>.rst (e.g. 588.bugfix.rst)
- if you don't have an issue number, change it to the pull request
  number after creating the PR
  - .bugfix: A bug fix for something the maintainers deemed an
    improper undesired behavior that got corrected to match
    pre-agreed expectations.
  - .feature: A new behavior, public APIs. That sort of stuff.
  - .deprecation: A declaration of future API removals and breaking
    changes in behavior.
  - .breaking: When something public is removed in a breaking way.
    Could be deprecated in an earlier release.
  - .doc: Notable updates to the documentation structure or build
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Fixed issue with non-ascii contents in doctest text files
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```
  Use the past tense or the present tense a non-imperative mood,
  referring to what's changed compared to the last released version
  of this project.

codspeed-hq · 2026-02-23T14:31:38Z

Merging this PR will not alter performance

✅ 59 untouched benchmarks

_{Comparing themylogin:master (481c13e) with master (830ae44)}

codecov · 2026-02-23T14:31:57Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.78%. Comparing base (4ec897b) to head (481c13e).
⚠️ Report is 5 commits behind head on master.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##           master   #12136   +/-   ##
=======================================
  Coverage   98.78%   98.78%           
=======================================
  Files         128      128           
  Lines       45297    45315   +18     
  Branches     2403     2405    +2     
=======================================
+ Hits        44747    44766   +19     
  Misses        390      390           
+ Partials      160      159    -1

Flag	Coverage Δ
CI-GHA	`98.64% <100.00%> (+<0.01%)`	⬆️
OS-Linux	`98.38% <100.00%> (+<0.01%)`	⬆️
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Py-3.13.11	`?`
Py-3.13.12	`98.21% <100.00%> (+0.74%)`	⬆️
Py-3.14.2	`?`
Py-3.14.3	`98.16% <100.00%> (+0.74%)`	⬆️
Py-3.14.3t	`97.26% <100.00%> (+<0.01%)`	⬆️
Py-pypy3.11.13-7.3.20	`97.29% <100.00%> (+<0.01%)`	⬆️
VM-macos	`97.63% <100.00%> (+<0.01%)`	⬆️
VM-ubuntu	`98.38% <100.00%> (+<0.01%)`	⬆️
VM-windows	`96.74% <100.00%> (+<0.01%)`	⬆️

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CHANGES/12136.bugfix.rst

tests/test_client_exceptions.py

Dreamsorcerer · 2026-02-23T17:28:56Z

I think this is an example of bugs getting introduced due to supporting non-ssl builds. I'm thinking it might be time to drop support for non-ssl builds soon.

webknjaz · 2026-02-23T18:35:38Z

I think this is an example of bugs getting introduced due to supporting non-ssl builds. I'm thinking it might be time to drop support for non-ssl builds soon.

Fair. I think "missing openssl" as a thing is coming from the late Python 2 epoch. OTOH, nowadays this might be a property of less common runtimes (pyodide etc).

CHANGES/12136.bugfix.rst

tests/test_client_exceptions.py

aiohttp/client_exceptions.py

…ttribute '_os_error'. ClientConnectorCertificateError is a subclass of ClientConnectorError and should have all of its attributes (LSP). However, when I try to access the os_error attribute, I get the mentioned exception.

aiohttp/client_exceptions.py

for more information, see https://pre-commit.ci

patchback · 2026-02-26T22:58:33Z

Backport to 3.13: 💚 backport PR created

✅ Backport PR branch: patchback/backports/3.13/c0f1513c37cb145b2618aeffd8f58d2f0cf230ab/pr-12136

Backported as #12147

🤖 @patchback
I'm built with octomachinery and
my source is open — https://github.com/sanitizers/patchback-github-app.

…ttribute '_os_error'. (#12136) (cherry picked from commit c0f1513)

patchback · 2026-02-26T22:58:48Z

Backport to 3.14: 💚 backport PR created

✅ Backport PR branch: patchback/backports/3.14/c0f1513c37cb145b2618aeffd8f58d2f0cf230ab/pr-12136

Backported as #12148

🤖 @patchback
I'm built with octomachinery and
my source is open — https://github.com/sanitizers/patchback-github-app.

…ttribute '_os_error'. (#12136) (cherry picked from commit c0f1513)

…torCertificateError' object has no attribute '_os_error'. (#12148) **This is a backport of PR #12136 as merged into master (c0f1513).** Co-authored-by: themylogin <themylogin@gmail.com>

…torCertificateError' object has no attribute '_os_error'. (#12147) **This is a backport of PR #12136 as merged into master (c0f1513).** Co-authored-by: themylogin <themylogin@gmail.com>

themylogin requested a review from asvetlov as a code owner February 23, 2026 14:20

themylogin force-pushed the master branch from 04a94a0 to 3ad0206 Compare February 23, 2026 14:22

themylogin requested a review from webknjaz as a code owner February 23, 2026 14:22

psf-chronographer bot added the bot:chronographer:provided There is a change note present in this PR label Feb 23, 2026

themylogin force-pushed the master branch from 3ad0206 to 4ea4155 Compare February 23, 2026 14:24

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webknjaz mentioned this pull request Feb 24, 2026

Introduce an initial LLM Usage Policy jazzband/pip-tools#2318

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themylogin force-pushed the master branch 4 times, most recently from e0bd413 to d7dd4fe Compare February 25, 2026 09:39

themylogin force-pushed the master branch from d7dd4fe to 6105d7e Compare February 25, 2026 09:41

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Dreamsorcerer and others added 2 commits February 26, 2026 22:40

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[pre-commit.ci] auto fixes from pre-commit.com hooks

481c13e

for more information, see https://pre-commit.ci

Dreamsorcerer added backport-3.13 Trigger automatic backporting to the 3.13 release branch by Patchback robot backport-3.14 Trigger automatic backporting to the 3.14 release branch by Patchback robot labels Feb 26, 2026

Dreamsorcerer merged commit c0f1513 into aio-libs:master Feb 26, 2026
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patchback bot pushed a commit that referenced this pull request Feb 26, 2026

Fix AttributeError: 'ClientConnectorCertificateError' object has no a…

3acb89c

…ttribute '_os_error'. (#12136) (cherry picked from commit c0f1513)

patchback bot mentioned this pull request Feb 26, 2026

[PR #12136/c0f1513c backport][3.13] Fix AttributeError: 'ClientConnectorCertificateError' object has no attribute '_os_error'. #12147

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patchback bot pushed a commit that referenced this pull request Feb 26, 2026

Fix AttributeError: 'ClientConnectorCertificateError' object has no a…

24e32f6

…ttribute '_os_error'. (#12136) (cherry picked from commit c0f1513)

patchback bot mentioned this pull request Feb 26, 2026

[PR #12136/c0f1513c backport][3.14] Fix AttributeError: 'ClientConnectorCertificateError' object has no attribute '_os_error'. #12148

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Fix AttributeError: 'ClientConnectorCertificateError' object has no attribute '_os_error'.#12136

Fix AttributeError: 'ClientConnectorCertificateError' object has no attribute '_os_error'.#12136
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themylogin commented Feb 23, 2026

What do these changes do?

Are there changes in behavior for the user?

Is it a substantial burden for the maintainers to support this?

Checklist

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Merging this PR will not alter performance

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