MkDocs builds perfectly locally, but gets stuck on Read the Docs

[Octelly]

Details

• Read the Docs project URL: https://readthedocs.org/projects/pluralkitpy/
• Build URL (if applicable): https://pluralkit.johnystar.moe/
• Read the Docs username (if applicable): Johnystar_CZ

Expected Result

Successfully build the docs just like I can do locally with mkdocs build or mkdocs serve

Actual Result

Always gets stuck at

ERROR   -  Config value: 'markdown_extensions'. Error: unsupported callable 

Aborted with 1 Configuration Errors!

I honestly have no clue if this is a bug or if I did something wrong, I at least triple checked everything, so I hope someone more experienced can help me.

[nmichlo]

I had exactly the same issue.

The problem is the emoji markdown plugin:

markdown_extensions:
  - pymdownx.emoji:
      emoji_index: !!python/name:materialx.emoji.twemoji
      emoji_generator: !!python/name:materialx.emoji.to_svg

Examining the step just before the error at cat mkdocs.yml. The problem seems to be that readthedocs generates a custom version of the mkdocs.yml file by parsing it, injecting keys and resaving the file.

This process is not able to handle the oddly formatted values for emoji_index and emoji_generator which become null.

markdown_extensions:
  - pymdownx.emoji:
      emoji_index: null
      emoji_generator: null

I have tried quoting these values, which preserves them, but mkdocs itself does then not support the quoted quotations (tested this locally too).

[humitos]

This problem is solved in #7507 and will be deployed tomorrow or the next week.