Import errro RemovedInSphinx40Warning

[cvanelteren]

Describe the bug

When buildings docs I am getting

Could not import extension sphinx.builders.epub3 (exception: cannot import name 'RemovedInSphinx40Warning' from 'sphinx.deprecation' (/home/casper/miniconda3/lib/python3.9/site-packages/sphinx/deprecation.py))

How to Reproduce

git clone https://github.com/sphinx-doc/sphinx
cd $sphinx && python setup.py install
git clone https://github.com/cvanelteren/Plexsim
cd Plexsim && make html

Expected behavior

Build the docs without error.

Tested on 4.1.0 and latest 4.2.0 dev

Your project

https://github.com/cvanelteren/Plexsim

Screenshots

Running Sphinx v4.1.0

Extension error:
Could not import extension sphinx.builders.epub3 (exception: cannot import name 'RemovedInSphinx40Warning' from 'sphinx.deprecation' (/home/casper/miniconda3/lib/python3.9/site-packages/sphinx/deprecation.py))
make: *** [Makefile:19: html] Error 2

OS

Linux arch 5.12.14

Python version

3.9.6

Sphinx version

4.1.0 / 4.2.0

Sphinx extensions

sphinx.ext.autodoc, sphinx.ext.napoleon, sphinxemoji.sphinxemoji, sphinx.ext.autosummary

Extra tools

No response

Additional context

No response

[cvanelteren]

As a workaround 4.0 works fine for me!

[jakobandersen]

Duplicate of #9434?

[cvanelteren]

Ah yes. Didn't see it my bad!