ExtensionError: Could not import extension sphinx.builders.latex

[CarsonPagel]

Describe the bug

sphinx.errors.ExtensionError: Could not import extension sphinx.builders.latex (exception: No module named 'roman_numerals')

How to Reproduce

sphinx-err-azdyvsyn.log

Environment Information

Platform:              win32; (Windows-11-10.0.26100-SP0)
Python version:        3.13.3 (tags/v3.13.3:6280bb5, Apr  8 2025, 14:47:33) [MSC v.1943 64 bit (AMD64)])
Python implementation: CPython
Sphinx version:        8.2.3
Docutils version:      0.21.2
Jinja2 version:        3.1.6
Pygments version:      2.19.2

Sphinx extensions

Additional context

    Traceback (most recent call last):
      File "C:\Users\userl\AppData\Local\pypoetry\Cache\virtualenvs\python-reporting-5iUxT0VP-py3.13\Lib\site-packages\sphinx\registry.py", line 541, in load_extension
        mod = import_module(extname)
      File "C:\Users\userl\AppData\Local\Programs\Python\Python313\Lib\importlib\__init__.py", line 88, in import_module
        return _bootstrap._gcd_import(name[level:], package, level)
               ~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
      File "<frozen importlib._bootstrap>", line 1387, in _gcd_import
      File "<frozen importlib._bootstrap>", line 1360, in _find_and_load
      File "<frozen importlib._bootstrap>", line 1331, in _find_and_load_unlocked
      File "<frozen importlib._bootstrap>", line 935, in _load_unlocked
      File "<frozen importlib._bootstrap_external>", line 1026, in exec_module
      File "<frozen importlib._bootstrap>", line 488, in _call_with_frames_removed
      File "C:\Users\userl\AppData\Local\pypoetry\Cache\virtualenvs\python-reporting-5iUxT0VP-py3.13\Lib\site-packages\sphinx\builders\latex\__init__.py", line 36, in <module>
        from sphinx.writers.latex import LaTeXTranslator, LaTeXWriter
      File "C:\Users\userl\AppData\Local\pypoetry\Cache\virtualenvs\python-reporting-5iUxT0VP-py3.13\Lib\site-packages\sphinx\writers\latex.py", line 15, in <module>
        from roman_numerals import RomanNumeral
    ModuleNotFoundError: No module named 'roman_numerals'
    
    The above exception was the direct cause of the following exception:
    
    Traceback (most recent call last):
      File "C:\Users\userl\AppData\Local\pypoetry\Cache\virtualenvs\python-reporting-5iUxT0VP-py3.13\Lib\site-packages\sphinx\cmd\build.py", line 414, in build_main
        app = Sphinx(
            srcdir=args.sourcedir,
        ...<14 lines>...
            exception_on_warning=args.exception_on_warning,
        )
      File "C:\Users\userl\AppData\Local\pypoetry\Cache\virtualenvs\python-reporting-5iUxT0VP-py3.13\Lib\site-packages\sphinx\application.py", line 287, in __init__
        self.setup_extension(extension)
        ~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^
      File "C:\Users\userl\AppData\Local\pypoetry\Cache\virtualenvs\python-reporting-5iUxT0VP-py3.13\Lib\site-packages\sphinx\application.py", line 489, in setup_extension
        self.registry.load_extension(self, extname)
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^
      File "C:\Users\userl\AppData\Local\pypoetry\Cache\virtualenvs\python-reporting-5iUxT0VP-py3.13\Lib\site-packages\sphinx\registry.py", line 544, in load_extension
        raise ExtensionError(
            __('Could not import extension %s') % extname, err
        ) from err
    sphinx.errors.ExtensionError: Could not import extension sphinx.builders.latex (exception: No module named 'roman_numerals')

[CarsonPagel]

Build successful after downgrading roman-numerals-py to 3.1.

[AA-Turner]

@CarsonPagel can you confirm that the error returns with pip install roman-numerals==4.0.0?

A

[CarsonPagel]

Changing the [tool.poetry.dependencies] roman-numerals to "=4.0.0" resulted in the error log posted above.

"<4.0.0" downgraded the dependency to 3.1.0 and then the build was successful.

[AA-Turner]

@CarsonPagel can you try with ==4.0.0 and paste pip freeze & the full Sphinx output with --show-traceback?

[jason-burbach]

I can confirm that pinning the roman-numerals version to 4.0.0 fixes the issue in my project.

Version 4.1.0 exhibits the same behavior as described in this Issue.

[AA-Turner]

@jason-burbach can you provide the same pip freeze output?

What does import roman_numerals do when 4.1 is installed?

A

[jason-burbach]

Unfortunately, I cannot. :-(

[AA-Turner]

It is impossible to debug packaging issues without environment information.

[jason-burbach]

I am not allowed to paste from my company CLI onto the internet.

I'm simply letting you know that your suggestion to pin to 4.0.0 worked for my case.

[AA-Turner]

@jason-burbach are you able to confirm that, with roman-numerals 4.1, importing the module raises no errors and gives an actual module object?

I'm trying to work out if this is a packaging issue or an actual bug in the code.

A

[jason-burbach]

I can confirm that when I switch back to 4.1.0, then the sphinx documents build fine again. 👀 Which is kinda odd. The import roman_numerals also works fine from a python shell.

I can tell you that I am running on a RHEL 8 OS and that after I update from roman-numerals 4.0.0 --> 4.1.0 in my venv, everything works as expected again.

Could it be they pushed an update to that version? Or that the 4.0.0 came with some dependency that was absent from the 4.1.0 artifact?

[deX-de]

I'm having the same issue. It seems like poetry is deleting the roman_numerals package from my site-packages directory within my environment. When I delete both roman_numerals_py-4.1.0.dist-info and roman_numerals-4.1.0.dist-info manually and run poetry install again the roman_numerals package reappears.

Interestingly, roman_numerals doesn't disappear when I downgrade from 4.1.0 to 3.1.0, however, after updating (both roman-numerals and roman-numerals-py) from 3.1.0 back to 4.1.0 it disappears again.

I could reproduce this issue on both my macOS device and on a GitLab runner running Linux.

[AA-Turner]

@deX-de is this only with Poetry? Does it reproduce when using another package manager?

A