Build broken due to TypeError: 'generator' object is not subscriptable

[m4sterbunny]

Describe the bug

This built fine locally for me.

When I tried to force a build from your interface this Exception occurred:
File "/home/docs/checkouts/readthedocs.org/user_builds/demo-zoom/envs/latest/lib/python3.7/site-packages/sphinx/builders/latex/init.py", line 201, in write
if toctrees[0].get('maxdepth') > 0:
TypeError: 'generator' object is not subscriptable

How to Reproduce

git clone --no-single-branch --depth 50 https://github.com/m4sterbunny/Demo.git .
git checkout --force origin/master
git clean -d -f -f
python3.7 -mvirtualenv /home/docs/checkouts/readthedocs.org/user_builds/demo-zoom/envs/latest
/home/docs/checkouts/readthedocs.org/user_builds/demo-zoom/envs/latest/bin/python -m pip install --upgrade --no-cache-dir pip setuptools
/home/docs/checkouts/readthedocs.org/user_builds/demo-zoom/envs/latest/bin/python -m pip install --upgrade --no-cache-dir mock==1.0.1 pillow==5.4.1 alabaster>=0.7,<0.8,!=0.7.5 commonmark==0.8.1 recommonmark==0.5.0 sphinx<2 sphinx-rtd-theme<0.5 readthedocs-sphinx-ext<2.2
cat source/conf.py
/home/docs/checkouts/readthedocs.org/user_builds/demo-zoom/envs/latest/bin/python -m sphinx -T -b html -d _build/doctrees -D language=en . _build/html
/home/docs/checkouts/readthedocs.org/user_builds/demo-zoom/envs/latest/bin/python -m sphinx -T -b readthedocssinglehtmllocalmedia -d _build/doctrees -D language=en . _build/localmedia
/home/docs/checkouts/readthedocs.org/user_builds/demo-zoom/envs/latest/bin/python -m sphinx -b latex -D language=en -d _build/doctrees . _build/latex
Running Sphinx v1.8.5
loading translations [en]... done
making output directory...
loading pickled environment... done
building [mo]: targets for 0 po files that are out of date
building [latex]: all documents
updating environment: 0 added, 0 changed, 0 removed
looking for now-outdated files... none found
processing Showcasing.tex...
Exception occurred:
File "/home/docs/checkouts/readthedocs.org/user_builds/demo-zoom/envs/latest/lib/python3.7/site-packages/sphinx/builders/latex/init.py", line 201, in write
if toctrees[0].get('maxdepth') > 0:
TypeError: 'generator' object is not subscriptable
The full traceback has been saved in /tmp/sphinx-err-omlwgho4.log,

Expected behavior

This built fine locally. I expected you to build it too!
Outputs here: https://demo-zoom.readthedocs.io/en/latest/pages/

Your project

https://readthedocs.org/projects/demo-zoom

Screenshots

No response

OS

Win 10 with Ubuntu

Python version

Python 3

Sphinx version

How do I even get that Sphinx -v does not work, nor variants of

Sphinx extensions

No response

Extra tools

No response

Additional context

Works for me locally. What's up?

[astrojuanlu]

Similar to #9727, pin docutils<0.18 in your requirements.

[astrojuanlu]

See also readthedocs/readthedocs.org#8616.

[m4sterbunny]

Tried to follow the docs, but despite specifying which Sphinx -- locally and remotely I seem to be on 1.8.5:

[astrojuanlu]

The .readthedocs.yaml file should be at the root of the repository, please try moving it

[peterjc]

Just noticed this started 2 or 3 days ago for me on RTD:
https://readthedocs.org/projects/thapbi-pict/builds/

Exception occurred:
  File "/home/docs/checkouts/readthedocs.org/user_builds/thapbi-pict/envs/latest/lib/python3.7/site-packages/sphinx/builders/latex/__init__.py", line 201, in write
    if toctrees[0].get('maxdepth') > 0:
TypeError: 'generator' object is not subscriptable

Good:
Jinja2-3.0.2 MarkupSafe-2.0.1 Pygments-2.10.0 alabaster-0.7.12 babel-2.9.1 certifi-2021.10.8 charset-normalizer-2.0.7 commonmark-0.8.1 docutils-0.17.1 future-0.18.2 idna-3.3 imagesize-1.2.0 mock-1.0.1 packaging-21.0 pillow-5.4.1 pyparsing-3.0.1 pytz-2021.3 readthedocs-sphinx-ext-2.1.4 recommonmark-0.5.0 requests-2.26.0 six-1.16.0 snowballstemmer-2.1.0 sphinx-1.8.5 sphinx-rtd-theme-0.4.3 sphinxcontrib-serializinghtml-1.1.5 sphinxcontrib-websupport-1.2.4 urllib3-1.26.7

Bad:
Jinja2-3.0.2 MarkupSafe-2.0.1 Pygments-2.10.0 alabaster-0.7.12 babel-2.9.1 certifi-2021.10.8 charset-normalizer-2.0.7 commonmark-0.8.1 docutils-0.18 future-0.18.2 idna-3.3 imagesize-1.2.0 mock-1.0.1 packaging-21.0 pillow-5.4.1 pyparsing-3.0.3 pytz-2021.3 readthedocs-sphinx-ext-2.1.4 recommonmark-0.5.0 requests-2.26.0 six-1.16.0 snowballstemmer-2.1.0 sphinx-1.8.5 sphinx-rtd-theme-0.4.3 sphinxcontrib-serializinghtml-1.1.5 sphinxcontrib-websupport-1.2.4 urllib3-1.26.7

i.e. Updated from docutils-0.17.1 (working) to docutils-0.18 (broken)

[m4sterbunny]

I had tried that in my wanderings in the wilderness; but to no effect:

[astrojuanlu]

@m4sterbunny You didn't move your .readthedocs.yaml file yet, or at least I don't see it in your demo project. If you do, please link to the corresponding build or commit.

@peterjc Yes, this is caused by docutils 0.18, see the linked issues in my comments above.

[m4sterbunny]

OK -- so I pushed rather than just looking local. Interestingly I am now getting different Sphinx version locally compared to your Build:

[m4sterbunny]

But the RtD build fails with a new error (whereas local build completes):
[https://readthedocs.org/projects/demo-zoom/builds/15124864/]

Sphinx error:
master file /home/docs/checkouts/readthedocs.org/user_builds/demo-zoom/checkouts/latest/index.rst not found

[astrojuanlu]

@m4sterbunny The .readthedocs.yaml file is only used by Read the Docs, it has no effect locally.

I see that the generator problem was solved after moving the config file to the root of the repository. Please open another issue with the current problem.

[astrojuanlu]

Also, notice that Sphinx and Read the Docs have separate issue trackers. The former is this one, the latter is https://github.com/readthedocs/readthedocs.org/issues/. If your problem is with Sphinx it should be here, if it's with Read the Docs it should be there.