Local variable "sitedir" is not defined since Python 3.15.0-beta.1

[FriedrichFroebel]

Describe the bug

GitHub Actions just switched from Python 3.15.0-alpha.8 to 3.15.0-beta.1 and I am receiving the following error when running sphinx-build -W -b doctest doc/api/ tmp or nearly all other commands:

Error in import line from /opt/hostedtoolcache/Python/3.15.0-beta.1/x64/lib/python3.15/site-packages/sphinxcontrib_jsmath-1.0.1-py3.7-nspkg.pth: import sys, types, os;has_mfs = sys.version_info > (3, 5);p = os.path.join(sys._getframe(1).f_locals['sitedir'], *('sphinxcontrib',));importlib = has_mfs and __import__('importlib.util');has_mfs and __import__('importlib.machinery');m = has_mfs and sys.modules.setdefault('sphinxcontrib', importlib.util.module_from_spec(importlib.machinery.PathFinder.find_spec('sphinxcontrib', [os.path.dirname(p)])));m = m or sys.modules.setdefault('sphinxcontrib', types.ModuleType('sphinxcontrib'));mp = (m or []) and m.__dict__.setdefault('__path__',[]);(p not in mp) and mp.append(p)
  Traceback (most recent call last):
    File "<frozen site>", line 319, in _exec_imports
    File "<string>", line 1, in <module>
  KeyError: "local variable ''sitedir'' is not defined"

How to Reproduce

Install sphinx and run anything importing Python modules, like the Sphinx build, flake8, tests etc.

Environment Information

Successfully installed Jinja2-3.1.6 MarkupSafe-3.0.3 Pygments-2.20.0 alabaster-1.0.0 babel-2.18.0 certifi-2026.4.22 charset_normalizer-3.4.7 djvulibre-python-0.9.3 docutils-0.22.4 flake8-7.3.0 idna-3.13 imagesize-1.5.0 mccabe-0.7.0 numpy-2.4.4 pep8-naming-0.15.1 pycairo-1.29.0 pycodestyle-2.14.0 pyflakes-3.4.0 requests-2.33.1 roman-numerals-4.1.0 snowballstemmer-3.0.1 sphinx-9.1.0 sphinxcontrib-applehelp-2.0.0 sphinxcontrib-devhelp-2.0.0 sphinxcontrib-htmlhelp-2.1.0 sphinxcontrib-jsmath-1.0.1 sphinxcontrib-qthelp-2.0.0 sphinxcontrib-serializinghtml-2.0.0 urllib3-2.7.0

Sphinx extensions

Additional context

No response

[hugovk]

First of all, thank you for testing the 3.15 pre-releases and reporting this bug!

Also reproducible with CPython docs:

Details

❯ make -C Doc clean venv html PYTHON=3.15
rm -rf ./venv
rm -rf build/*
Creating venv in ./venv
Using CPython 3.15.0b1 interpreter at: /Library/Frameworks/Python.framework/Versions/3.15/bin/python3.15
Creating virtual environment at: ./venv
Activate with: source venv/bin/activate
warning: The `--pylock` option is experimental and may change without warning. Pass `--preview-features pylock` to disable this warning.
Using Python 3.15.0b1 environment at: venv
Prepared 28 packages in 6ms
Installed 28 packages in 91ms
 + alabaster==1.0.0
 + babel==2.18.0
 + blurb==2.0.0
 + certifi==2026.4.22
 + charset-normalizer==3.4.7
 + docutils==0.21.2
 + idna==3.13
 + imagesize==1.5.0
 + jinja2==3.1.6
 + linklint==1.0.0
 + markupsafe==2.1.5
 + packaging==24.2
 + pygments==2.20.0
 + python-docs-theme==2026.4
 + requests==2.33.1
 + roman-numerals==4.1.0
 + roman-numerals-py==4.1.0
 + snowballstemmer==2.2.0
 + sphinx==8.2.3
 + sphinx-notfound-page==1.0.4
 + sphinxcontrib-applehelp==2.0.0
 + sphinxcontrib-devhelp==2.0.0
 + sphinxcontrib-htmlhelp==2.1.0
 + sphinxcontrib-jsmath==1.0.1
 + sphinxcontrib-qthelp==2.0.0
 + sphinxcontrib-serializinghtml==2.0.0
 + sphinxext-opengraph==0.13.0
 + urllib3==2.6.3
The venv has been created in the ./venv directory
mkdir -p build
Error in import line from /Users/hugo/github/python/cpython/main/Doc/venv/lib/python3.15/site-packages/sphinxcontrib_jsmath-1.0.1-py3.7-nspkg.pth: import sys, types, os;has_mfs = sys.version_info > (3, 5);p = os.path.join(sys._getframe(1).f_locals['sitedir'], *('sphinxcontrib',));importlib = has_mfs and __import__('importlib.util');has_mfs and __import__('importlib.machinery');m = has_mfs and sys.modules.setdefault('sphinxcontrib', importlib.util.module_from_spec(importlib.machinery.PathFinder.find_spec('sphinxcontrib', [os.path.dirname(p)])));m = m or sys.modules.setdefault('sphinxcontrib', types.ModuleType('sphinxcontrib'));mp = (m or []) and m.__dict__.setdefault('__path__',[]);(p not in mp) and mp.append(p)
  Traceback (most recent call last):
    File "<frozen site>", line 319, in _exec_imports
    File "<string>", line 1, in <module>
  KeyError: "local variable ''sitedir'' is not defined"
Error in import line from /Users/hugo/github/python/cpython/main/Doc/venv/lib/python3.15/site-packages/sphinxcontrib_jsmath-1.0.1-py3.7-nspkg.pth: import sys, types, os;has_mfs = sys.version_info > (3, 5);p = os.path.join(sys._getframe(1).f_locals['sitedir'], *('sphinxcontrib',));importlib = has_mfs and __import__('importlib.util');has_mfs and __import__('importlib.machinery');m = has_mfs and sys.modules.setdefault('sphinxcontrib', importlib.util.module_from_spec(importlib.machinery.PathFinder.find_spec('sphinxcontrib', [os.path.dirname(p)])));m = m or sys.modules.setdefault('sphinxcontrib', types.ModuleType('sphinxcontrib'));mp = (m or []) and m.__dict__.setdefault('__path__',[]);(p not in mp) and mp.append(p)
  Traceback (most recent call last):
    File "<frozen site>", line 319, in _exec_imports
    File "<string>", line 1, in <module>
  KeyError: "local variable ''sitedir'' is not defined"
blurb version 2.0.0
Error in import line from /Users/hugo/github/python/cpython/main/Doc/venv/lib/python3.15/site-packages/sphinxcontrib_jsmath-1.0.1-py3.7-nspkg.pth: import sys, types, os;has_mfs = sys.version_info > (3, 5);p = os.path.join(sys._getframe(1).f_locals['sitedir'], *('sphinxcontrib',));importlib = has_mfs and __import__('importlib.util');has_mfs and __import__('importlib.machinery');m = has_mfs and sys.modules.setdefault('sphinxcontrib', importlib.util.module_from_spec(importlib.machinery.PathFinder.find_spec('sphinxcontrib', [os.path.dirname(p)])));m = m or sys.modules.setdefault('sphinxcontrib', types.ModuleType('sphinxcontrib'));mp = (m or []) and m.__dict__.setdefault('__path__',[]);(p not in mp) and mp.append(p)
  Traceback (most recent call last):
    File "<frozen site>", line 319, in _exec_imports
    File "<string>", line 1, in <module>
  KeyError: "local variable ''sitedir'' is not defined"
Error in import line from /Users/hugo/github/python/cpython/main/Doc/venv/lib/python3.15/site-packages/sphinxcontrib_jsmath-1.0.1-py3.7-nspkg.pth: import sys, types, os;has_mfs = sys.version_info > (3, 5);p = os.path.join(sys._getframe(1).f_locals['sitedir'], *('sphinxcontrib',));importlib = has_mfs and __import__('importlib.util');has_mfs and __import__('importlib.machinery');m = has_mfs and sys.modules.setdefault('sphinxcontrib', importlib.util.module_from_spec(importlib.machinery.PathFinder.find_spec('sphinxcontrib', [os.path.dirname(p)])));m = m or sys.modules.setdefault('sphinxcontrib', types.ModuleType('sphinxcontrib'));mp = (m or []) and m.__dict__.setdefault('__path__',[]);(p not in mp) and mp.append(p)
  Traceback (most recent call last):
    File "<frozen site>", line 319, in _exec_imports
    File "<string>", line 1, in <module>
  KeyError: "local variable ''sitedir'' is not defined"
sphinx-build 8.2.3
Building NEWS from Misc/NEWS.d with blurb
Error in import line from /Users/hugo/github/python/cpython/main/Doc/venv/lib/python3.15/site-packages/sphinxcontrib_jsmath-1.0.1-py3.7-nspkg.pth: import sys, types, os;has_mfs = sys.version_info > (3, 5);p = os.path.join(sys._getframe(1).f_locals['sitedir'], *('sphinxcontrib',));importlib = has_mfs and __import__('importlib.util');has_mfs and __import__('importlib.machinery');m = has_mfs and sys.modules.setdefault('sphinxcontrib', importlib.util.module_from_spec(importlib.machinery.PathFinder.find_spec('sphinxcontrib', [os.path.dirname(p)])));m = m or sys.modules.setdefault('sphinxcontrib', types.ModuleType('sphinxcontrib'));mp = (m or []) and m.__dict__.setdefault('__path__',[]);(p not in mp) and mp.append(p)
  Traceback (most recent call last):
    File "<frozen site>", line 319, in _exec_imports
    File "<string>", line 1, in <module>
  KeyError: "local variable ''sitedir'' is not defined"
Error in import line from /Users/hugo/github/python/cpython/main/Doc/venv/lib/python3.15/site-packages/sphinxcontrib_jsmath-1.0.1-py3.7-nspkg.pth: import sys, types, os;has_mfs = sys.version_info > (3, 5);p = os.path.join(sys._getframe(1).f_locals['sitedir'], *('sphinxcontrib',));importlib = has_mfs and __import__('importlib.util');has_mfs and __import__('importlib.machinery');m = has_mfs and sys.modules.setdefault('sphinxcontrib', importlib.util.module_from_spec(importlib.machinery.PathFinder.find_spec('sphinxcontrib', [os.path.dirname(p)])));m = m or sys.modules.setdefault('sphinxcontrib', types.ModuleType('sphinxcontrib'));mp = (m or []) and m.__dict__.setdefault('__path__',[]);(p not in mp) and mp.append(p)
  Traceback (most recent call last):
    File "<frozen site>", line 319, in _exec_imports
    File "<string>", line 1, in <module>
  KeyError: "local variable ''sitedir'' is not defined"
PATH=./venv/bin:$PATH sphinx-build --builder html --doctree-dir build/doctrees --jobs auto   --fail-on-warning . build/html
Error in import line from /Users/hugo/github/python/cpython/main/Doc/venv/lib/python3.15/site-packages/sphinxcontrib_jsmath-1.0.1-py3.7-nspkg.pth: import sys, types, os;has_mfs = sys.version_info > (3, 5);p = os.path.join(sys._getframe(1).f_locals['sitedir'], *('sphinxcontrib',));importlib = has_mfs and __import__('importlib.util');has_mfs and __import__('importlib.machinery');m = has_mfs and sys.modules.setdefault('sphinxcontrib', importlib.util.module_from_spec(importlib.machinery.PathFinder.find_spec('sphinxcontrib', [os.path.dirname(p)])));m = m or sys.modules.setdefault('sphinxcontrib', types.ModuleType('sphinxcontrib'));mp = (m or []) and m.__dict__.setdefault('__path__',[]);(p not in mp) and mp.append(p)
  Traceback (most recent call last):
    File "<frozen site>", line 319, in _exec_imports
    File "<string>", line 1, in <module>
  KeyError: "local variable ''sitedir'' is not defined"
Error in import line from /Users/hugo/github/python/cpython/main/Doc/venv/lib/python3.15/site-packages/sphinxcontrib_jsmath-1.0.1-py3.7-nspkg.pth: import sys, types, os;has_mfs = sys.version_info > (3, 5);p = os.path.join(sys._getframe(1).f_locals['sitedir'], *('sphinxcontrib',));importlib = has_mfs and __import__('importlib.util');has_mfs and __import__('importlib.machinery');m = has_mfs and sys.modules.setdefault('sphinxcontrib', importlib.util.module_from_spec(importlib.machinery.PathFinder.find_spec('sphinxcontrib', [os.path.dirname(p)])));m = m or sys.modules.setdefault('sphinxcontrib', types.ModuleType('sphinxcontrib'));mp = (m or []) and m.__dict__.setdefault('__path__',[]);(p not in mp) and mp.append(p)
  Traceback (most recent call last):
    File "<frozen site>", line 319, in _exec_imports
    File "<string>", line 1, in <module>
  KeyError: "local variable ''sitedir'' is not defined"
Running Sphinx v8.2.3
loading translations [en]... done
matplotlib is not installed, social cards will not be generated
making output directory... done
building [mo]: targets for 0 po files that are out of date
writing output...
building [html]: targets for 548 source files that are out of date
updating environment: [new config] 548 added, 0 changed, 0 removed
reading sources... [100%] whatsnew/changelog .. whatsnew/index
looking for now-outdated files... none found
pickling environment... done
checking consistency... /Users/hugo/github/python/cpython/main/Doc/howto/argparse.rst: document is referenced in multiple toctrees: ['howto/index', 'library/argparse'], selecting: library/argparse <- howto/argparse
done
preparing documents... done
copying assets...
copying downloadable files... [100%] includes/tzinfo_examples.py
copying static files...
Writing evaluated template result to /Users/hugo/github/python/cpython/main/Doc/build/html/_static/basic.css
Writing evaluated template result to /Users/hugo/github/python/cpython/main/Doc/build/html/_static/language_data.js
Writing evaluated template result to /Users/hugo/github/python/cpython/main/Doc/build/html/_static/documentation_options.js
Writing evaluated template result to /Users/hugo/github/python/cpython/main/Doc/build/html/_static/classic.css
Writing evaluated template result to /Users/hugo/github/python/cpython/main/Doc/build/html/_static/sidebar.js
copying static files: done
copying extra files...
copying extra files: done
copying assets: done
writing output... [100%] whatsnew/3.5 .. whatsnew/index
generating indices... genindex py-modindex done
writing additional pages... download index search opensearch done
copying images... [100%] using/win_install_freethreaded.png
dumping search index in English (code: en)... done
dumping object inventory... done
Writing glossary.json
profiling_trace: Injected 38 trace events into profiling-sampling-visualization.js
Linklint: unlinked 3584 refs: 2000 duplicate, 1584 self
build succeeded.

The HTML pages are in build/html.

Build finished. The HTML pages are in build/html.

Minimal repro:

❯ echo "import sys; sys._getframe(1).f_locals['sitedir']" > legacy.pth

❯ python3.14 -c "import site; site.addsitedir('.')"

❯ python3.15 -c "import site; site.addsitedir('.')"
Found existing alias for "python3.15". You should use: "p5"
Error in import line from /Users/hugo/github/python/cpython/main/legacy.pth: import sys; sys._getframe(1).f_locals['sitedir']
  Traceback (most recent call last):
    File "<frozen site>", line 319, in _exec_imports
    File "<string>", line 1, in <module>
      import site; site.addsitedir('.')
                  ~~~~~~~~~~~~~~~~^^^^^
  KeyError: "local variable ''sitedir'' is not defined"

Not reproducible in a8, but is in b1.

Bisects to PEP 829: python/cpython#149109, cc @warsaw.

[m-aciek]

Where is this pth file coming from? There's python 3.7 mentioned in its name. The only wheel published for related package (by pth file name) is this: https://pypi.org/project/sphinxcontrib-jsmath/#sphinxcontrib_jsmath-1.0.1-py2.py3-none-any.whl