errno and strerror attributes incorrectly set on socket errors wrapped by urllib #50720

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1. iritkatriel commented on Nov 30, 2021

   

   iritkatriel

   on Nov 30, 2021

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   Reproduced on 3.11:

   >>> from urllib.request import urlopen
   >>> try:
   ...     urlopen('http://www.pythonfoobarbaz.org')
   ... except Exception as exc:
   ...     err = exc
   ...     print('err:', err)
   ...     print('repr(err):', repr(err))
   ...     print('err.errno:', err.errno)
   ...     print('err.strerror:', err.strerror)
   ...     print('err.reason:', err.reason)
   ...     print('err.reason.errno:', err.reason.errno)
   ...     print('err.reason.strerror:', err.reason.strerror)
   ... 
   err: <urlopen error [Errno 8] nodename nor servname provided, or not known>
   repr(err): URLError(gaierror(8, 'nodename nor servname provided, or not known'))
   err.errno: None
   err.strerror: None
   err.reason: [Errno 8] nodename nor servname provided, or not known
   err.reason.errno: 8
   err.reason.strerror: nodename nor servname provided, or not known
2. iritkatriel

   added

   3.9 (EOL)end of lifeend of life

   3.10 (EOL)end of lifeend of life

   3.11only security fixesonly security fixes

   on Nov 30, 2021
3. ezio-melotti

   transferred this issue fromon Apr 10, 2022
4. iritkatriel

   added

   3.12only security fixesonly security fixes

   and removed

   3.9 (EOL)end of lifeend of life

   on Mar 1, 2023
5. serhiy-storchaka

   added this to Urllib issueson Jul 3, 2026
6. github-project-automation

   moved this to Todo in Urllib issueson Jul 3, 2026
7. vasiliyk commented on Oct 21, 2026

   

   vasiliyk

   on Oct 21, 2026

   Contributor

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   Still reproduces on 3.16.0a1+dev:

   >>> from urllib.request import urlopen
   >>> try:
   ...     urlopen('http://www.pythonfoobarbaz.org')
   ... except Exception as exc:
   ...     err = exc
   ...     print('err:', err)
   ...     print('repr(err):', repr(err))
   ...     print('err.errno:', err.errno)
   ...     print('err.strerror:', err.strerror)
   ...     print('err.reason:', err.reason)
   ...     print('err.reason.errno:', err.reason.errno)
   ...     print('err.reason.strerror:', err.reason.strerror)
   ... 
   err: <urlopen error [Errno 8] nodename nor servname provided, or not known>
   repr(err): URLError(gaierror(8, 'nodename nor servname provided, or not known'))
   err.errno: None
   err.strerror: None
   err.reason: [Errno 8] nodename nor servname provided, or not known
   err.reason.errno: 8
   err.reason.strerror: nodename nor servname provided, or not known

   URLError.__init__ sets only args and reason, so the OSError attributes are never set.

   Following the original patch:

   • in URLError.__init__, if reason is an OSError, copy its errno and strerror.
   • args, str() and repr() do not change, so the backward-compatibility concern does not apply.

   I can open a PR with tests if this approach is fine.
8. orsenthil commented on Oct 29, 2026

   

   orsenthil

   on Oct 29, 2026

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   @vasiliyk, please create the patch with the approach.

   👍React with 👍1Reacted by Vasiliy Kiryanov
9. vasiliyk commented on Oct 30, 2026

   

   vasiliyk

   on Oct 30, 2026

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   @orsenthil The PR is up - #160938. I added a a versionchanged note for 3.16 in urllib.error doc.
10. orsenthil

    moved this from Todo to In Progress in Urllib issueson Oct 31, 2026
11. orsenthil

    added a commit that references this issue on Oct 31, 2026

    Merge branch 'main' into pythongh-50720-urllib

    e10e451
12. orsenthil

    added

    3.16new features, bugs and security fixesnew features, bugs and security fixes

    and removed

    3.11only security fixesonly security fixes

    3.10 (EOL)end of lifeend of life

    3.12only security fixesonly security fixes

    on Oct 31, 2026
13. orsenthil commented on Oct 31, 2026

    

    orsenthil

    on Oct 31, 2026

    Member

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    Thanks for this patch. This shouldn't be backported as there is subtle scenario wherein if an old code was checking e.errno is None previously to fall back on OSError, it will break and will need a change.
14. orsenthil

    moved this from In Progress to Done in Urllib issueson Oct 31, 2026
15. orsenthil

    closed this as completedby moving to Done in Urllib issueson Oct 31, 2026
16. orsenthil

    added 2 commits that reference this issue on Oct 31, 2026

    gh-50720: Set errno and strerror on URLError wrapping an OSError (#16…

    ...

    2cf2dd6

    gh-50720: Copy winerror to URLError on Windows (#161047)

    0fd00ee