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@miss-islington miss-islington commented Nov 19, 2025

In Fedora, we've been given a slightly incomplete reproducer for a problematic
Python 3.14 color-related change in argparse that leads to an exception when
Python is used from mod_wsgi: https://bugzilla.redhat.com/2414940

mod_wsgi replaces sys.stdout with a custom object that raises OSError on .fileno():

https://github.com/GrahamDumpleton/mod_wsgi/blob/8460dbfcd5c7108892b3cde9fab7cbc1caa27886/src/server/wsgi_logger.c#L434-L440

This should be supported, as the documentation of fileno explicitly says:

An OSError is raised if the IO object does not use a file descriptor.

https://docs.python.org/3.14/library/io.html#io.IOBase.fileno

The previously expected exception inherits from OSError,
so it is still expected.

Fixes #141570
(cherry picked from commit 96f496a)

Co-authored-by: Miro Hrončok [email protected]
Co-authored-by: Cody Maloney [email protected]
Co-authored-by: Victor Stinner [email protected]

…ocumented (pythonGH-141716)

In Fedora, we've been given a slightly incomplete reproducer for a problematic
Python 3.14 color-related change in argparse that leads to an exception when
Python is used from mod_wsgi: https://bugzilla.redhat.com/2414940

mod_wsgi replaces sys.stdout with a custom object that raises OSError on .fileno():

https://github.com/GrahamDumpleton/mod_wsgi/blob/8460dbfcd5c7108892b3cde9fab7cbc1caa27886/src/server/wsgi_logger.c#L434-L440

This should be supported, as the documentation of fileno explicitly says:

> An OSError is raised if the IO object does not use a file descriptor.

https://docs.python.org/3.14/library/io.html#io.IOBase.fileno

The previously expected exception inherits from OSError,
so it is still expected.

Fixes python#141570
(cherry picked from commit 96f496a)

Co-authored-by: Miro Hrončok <[email protected]>
Co-authored-by: Cody Maloney <[email protected]>
Co-authored-by: Victor Stinner <[email protected]>
@vstinner vstinner merged commit 8c79688 into python:3.14 Nov 19, 2025
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4 participants