Bug 2416977

Summary: Python 3.15: ImportError: /usr/lib64/python3.15/site-packages/lxml/etree.cpython-315-x86_64-linux-gnu.so: undefined symbol: _PyByteArray_empty_string
Product: [Fedora] Fedora Reporter: Karolina Surma <ksurma>
Component: python-lxmlAssignee: Python Maintainers <python-maint>
Status: CLOSED NOTABUG QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: unspecified Docs Contact:
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Version: rawhideCC: cstratak, igor.raits, ksurma, lbalhar, me, mhroncok, mizdebsk, python-maint, python-packagers-sig
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Last Closed: 2025-11-25 11:46:05 UTC Type: Bug
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Bug Blocks: 2412434    

Description Karolina Surma 2025-11-25 10:04:53 UTC
python-et_xmlfile and others fail to build with Python 3.15.0a2 / fails to import lxml.etree.
We build lxml without tests for now, hence this is found in many packages that use it, rather than in the package build itself:

________ ERROR collecting et_xmlfile/tests/test_incremental_xmlfile.py _________
ImportError while importing test module '/builddir/build/BUILD/python-et_xmlfile-2.0.0-build/et_xmlfile-2.0.0/et_xmlfile/tests/test_incremental_xmlfile.py'.
Hint: make sure your test modules/packages have valid Python names.
Traceback:
/usr/lib64/python3.15/importlib/__init__.py:88: in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
et_xmlfile/tests/test_incremental_xmlfile.py:24: in <module>
    from .helper import compare_xml
et_xmlfile/tests/helper.py:5: in <module>
    from lxml.doctestcompare import LXMLOutputChecker, PARSE_XML
/usr/lib64/python3.15/site-packages/lxml/doctestcompare.py:38: in <module>
    from lxml import etree
E   ImportError: /usr/lib64/python3.15/site-packages/lxml/etree.cpython-315-x86_64-linux-gnu.so: undefined symbol: _PyByteArray_empty_string

The symbol was removed in https://github.com/python/cpython/pull/140128

https://docs.python.org/3.15/whatsnew/3.15.html

For all our attempts to build python-ratelimitingfilter with Python 3.15, see:
https://copr.fedorainfracloud.org/coprs/g/python/python3.15/package/python-et_xmlfile/

Testing and mass rebuild of packages is happening in copr.
You can follow these instructions to test locally in mock if your package builds with Python 3.15:
https://copr.fedorainfracloud.org/coprs/g/python/python3.15/

Let us know here if you have any questions.

Python 3.15 is planned to be included in Fedora 45.
To make that update smoother, we're building Fedora packages with all pre-releases of Python 3.15.
A build failure prevents us from testing all dependent packages (transitive [Build]Requires),
so if this package is required a lot, it's important for us to get it fixed soon.

We'd appreciate help from the people who know this package best,
but if you don't want to work on this now, let us know so we can try to work around it on our side.

Comment 1 Karolina Surma 2025-11-25 11:46:05 UTC
This has been caused by building against an old build of lxml - not a bug.