Somehow due to some dependency conflict resolution the Read The Docs build pipeline ended up installing v0.5 of the rtd sphinx theme instead of a newer version, which was somehow incompatible with the newer sphinx releases.
Traceback (most recent call last):
File "/home/docs/checkouts/readthedocs.org/user_builds/microbit-micropython/envs/latest/lib/python3.11/site-packages/sphinx/builders/html/__init__.py", line 1120, in handle_page
output = self.templates.render(templatename, ctx)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/docs/checkouts/readthedocs.org/user_builds/microbit-micropython/envs/latest/lib/python3.11/site-packages/readthedocs_ext/readthedocs.py", line 181, in rtd_render
content = old_render(template, render_context)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/docs/checkouts/readthedocs.org/user_builds/microbit-micropython/envs/latest/lib/python3.11/site-packages/sphinx/jinja2glue.py", line 200, in render
return self.environment.get_template(template).render(context)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/docs/checkouts/readthedocs.org/user_builds/microbit-micropython/envs/latest/lib/python3.11/site-packages/jinja2/environment.py", line 1304, in render
self.environment.handle_exception()
File "/home/docs/checkouts/readthedocs.org/user_builds/microbit-micropython/envs/latest/lib/python3.11/site-packages/jinja2/environment.py", line 939, in handle_exception
raise rewrite_traceback_stack(source=source)
File "/home/docs/checkouts/readthedocs.org/user_builds/microbit-micropython/envs/latest/lib/python3.11/site-packages/sphinx/themes/basic/page.html", line 10, in top-level template code
{%- extends "layout.html" %}
^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/docs/checkouts/readthedocs.org/user_builds/microbit-micropython/envs/latest/lib/python3.11/site-packages/sphinx_rtd_theme/layout.html", line 23, in top-level template code
<link rel="stylesheet" href="{{ pathto('_static/' + style, 1) }}" type="text/css" />
^^^^^^^^^^^^^^^^^^^^^^^^^
jinja2.exceptions.UndefinedError: 'style' is undefined
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
File "/home/docs/checkouts/readthedocs.org/user_builds/microbit-micropython/envs/latest/lib/python3.11/site-packages/sphinx/cmd/build.py", line 337, in build_main
app.build(args.force_all, args.filenames)
File "/home/docs/checkouts/readthedocs.org/user_builds/microbit-micropython/envs/latest/lib/python3.11/site-packages/sphinx/application.py", line 378, in build
self.builder.build_update()
File "/home/docs/checkouts/readthedocs.org/user_builds/microbit-micropython/envs/latest/lib/python3.11/site-packages/sphinx/builders/__init__.py", line 297, in build_update
self.build(to_build,
File "/home/docs/checkouts/readthedocs.org/user_builds/microbit-micropython/envs/latest/lib/python3.11/site-packages/sphinx/builders/__init__.py", line 367, in build
self.write(docnames, list(updated_docnames), method)
File "/home/docs/checkouts/readthedocs.org/user_builds/microbit-micropython/envs/latest/lib/python3.11/site-packages/sphinx/builders/__init__.py", line 614, in write
self._write_serial(sorted(docnames))
File "/home/docs/checkouts/readthedocs.org/user_builds/microbit-micropython/envs/latest/lib/python3.11/site-packages/sphinx/builders/__init__.py", line 624, in _write_serial
self.write_doc(docname, doctree)
File "/home/docs/checkouts/readthedocs.org/user_builds/microbit-micropython/envs/latest/lib/python3.11/site-packages/sphinx/builders/html/__init__.py", line 666, in write_doc
self.handle_page(docname, ctx, event_arg=doctree)
File "/home/docs/checkouts/readthedocs.org/user_builds/microbit-micropython/envs/latest/lib/python3.11/site-packages/sphinx/builders/html/__init__.py", line 1127, in handle_page
raise ThemeError(__("An error happened in rendering the page %s.\nReason: %r") %
sphinx.errors.ThemeError: An error happened in rendering the page accelerometer.
Reason: UndefinedError("'style' is undefined")
Theme error:
An error happened in rendering the page accelerometer.
Reason: UndefinedError("'style' is undefined")
Somehow due to some dependency conflict resolution the Read The Docs build pipeline ended up installing v0.5 of the rtd sphinx theme instead of a newer version, which was somehow incompatible with the newer sphinx releases.