Sphinx v5.2.0.post0: sphinx-rtd-theme Theme error: ValueError('too many values to unpack (expected 3)')

[seanlanter]

Describe the bug

unexpected 'Theme error' from sphinx-rtd-theme

• appears starting with 'Sphinx v5.2.0.post0'
• did not occur in 'Sphinx v5.1.1'

How to Reproduce

confirm that 'pip -install -U -r requirments.txt ' runs correctly, where the content of 'requirements.txt' is:

 sphinx
 sphinx-rtd-theme
 sphinx-copybutton
 sphinx-tabs
 sphinxcontrib-napoleon
 sphinx-autobuild
 pyyaml
 flask
 flask_cors

run the build command:

 sphinx-build -b html -a -W <source-dir> <output-dir>

observe the output:

 Running Sphinx v5.2.0.post0
 loading intersphinx inventory from https://docs.python.org/3/objects.inv...
 building [mo]: all of 0 po files
 building [html]: all source files
 updating environment: [new config] 19 added, 0 changed, 0 removed
 reading sources... [100%] tutorial/wander                                                                    
 looking for now-outdated files... none found
 pickling environment... done
 checking consistency... done
 preparing documents... done
 writing output... [  5%] background/4kinds                                                                   
 Theme error:
 An error happened in rendering the page background/4kinds.
 Reason: ValueError('too many values to unpack (expected 3)')

Expected behavior

No 'Theme error'.

Your project

https://gitlab.com/cnxeng/wordsmith

Screenshots

No response

OS

Mac Monterey 12.5.1, Windows 10

Python version

3.10

Sphinx version

5.2.0.post0

Sphinx extensions

sphinx.ext.autodoc, sphinx.ext.doctest, sphinx.ext.intersphinx, sphinx.ext.todo, sphinx.ext.coverage, sphinx.ext.imgmath, sphinx.ext.mathjax, sphinx.ext.ifconfig, sphinx.ext.viewcode, sphinx.ext.githubpages, sphinx_copybutton, sphinx_tabs.tabs, sphinx.ext.napoleon, sphinx.ext.autosectionlabel

Extra tools

No response

Additional context

No response

[rouault]

I also reproduce that with GDAL doc builds that have started to fail starting with this job https://github.com/OSGeo/gdal/actions/runs/3122251004/jobs/5064218826 (using v5.2.0.post0) whereas previous job https://github.com/OSGeo/gdal/actions/runs/3114759364/jobs/5050956471 (using 5.1.1) is succesful.

[AA-Turner]

Duplicates #10860

A