Extension error: Could not import extension myst_parser

[LucyWriter]

Greetings - has anyone experienced this error and fixed it?

Running Sphinx v4.5.0

Extension error:
Could not import extension myst_parser (exception: No module named 'myst_parser')
make: *** [html] Error 2

[chrisjsewell]

Heya, it appears that you have not installed myst-parser

[LucyWriter]

But I see this when I install - pip3 install myst-parser
Requirement already satisfied: myst-parser in /Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages (0.17.2)
Collecting sphinx<5,>=3.1
Using cached Sphinx-4.5.0-py3-none-any.whl (3.1 MB)

[chrisjsewell]

But perhaps you are running sphinx-build installed from a different Python environment?

[LucyWriter]

How can I check that?

[chrisjsewell]

Maybe which sphinx-build, can't remember if you can run pip -m sphinx 🤔

[LucyWriter]

Nothing seems to work - I've installed, uninstalled sphinx-doc and the extensions.
Running Sphinx v4.5.0

Extension error:
Could not import extension myst_parser (exception: No module named 'myst_parser')
make: *** [html] Error 2

Using this command worked before - pip3 install git+https://github.com/sphinx-doc/sphinx but now it's pulling in 5.1.0+ and I see error messages about incompatibility. Uninstalled it and then used brew install sphinx-doc. Still broken.

[Daraan]

I also had this problem. It was solved after I activated my environment once more after the installation.

Thank you past self; as I again ran into this problem.

[72757373656c6c]

I know this discussion is a little old, but perhaps this might help someone in the future. Regarding the original issue. As Daraan pointed out, this is a $PATH problem. The directory where myst-parser was installed was not in the $PATH.

When I began in the sphinx+myst world, I followed Paul Everitt's steps, which creates a python virtual environment.

To summarize with some modifications (YMMV 😄):

1. Create your documentation directory.

   mkdir -p src/project && cd src/project
   

2. Install python virtual environment

   python -m venv .venv
   

3. Activate virtual environment. Notice the terminal prompt change and the $PATH change.

   source .venv/bin/activate
   

4. Create the file, requirements.txt and add required packages. Change as needed. At a minimum, you need sphinx and myst-parser. The default theme is alabaster.

   sphinx
   myst-parser
   sphinx-book-theme
   sphinx-copybutton
   sphinx-togglebutton
   sphinx-design
   

5. Install requirements.

   pip install -r requirements.txt
   

6. Setup your sphinx documentation environment. There are a couple of prompts. See Paul's doc for a screenshot.

   sphinx-quickstart
   

7. Modify the conf.py as needed. Read the theme's documentation.

   cd source
   
   nano conf.py
   
   extensions = [
     "myst_parser",
     "sphinx_copybutton",
     "sphinx_design",
     "sphinx_togglebutton",
   ]
   
   myst_enable_extensions = [
     "attrs_block",
     "attrs_inline",
     "colon_fence",
     "deflist",
   ]
   
   source_suffix = { ".md": "markdown" }
   html_theme = "sphinx_book_theme"
   #html_theme = "alabaster"
   

8. Assuming all markdown, remove index.rst and add your own index.md file.

   nano index.md
   
   # Welcome 
   
   :::{toctree}
   :glob:
   :hidden:
   :maxdepth: 1
   
   [a-z]*
   :::
   

9. Create your documentation. Files end with .md. Read myst-parser documentation.

10. Create your html documentation. See documentation for other builders.

    cd ../
    make clean 
    make html
    firefox build/html/index.html
    

[agoose77]

Thanks for writing up the steps that you took here @72757373656c6c :) Python environment handling can be a source of confusion for new users, so it's good to have a comprehensive reply to point to :)