jupyter-book build: NotImplementedError on Windows Python 3.8

Maintainer Edit:

This issue is related to jupyter/nbclient#85

So it looks like, for now on Windows, you need to use Python 3.7.

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Describe the bug

I am following the tutorial set-up https://jupyterbook.org/start/build.html In the second step it says use jupyter-book build mybookname to build the book - i get an error. Here is an error: File "C:\Program Files\Python38\lib\asyncio\events.py", line 501, in add_reader raise NotImplementedError NotImplementedError Here is a screenshot of my terminal:

To Reproduce

Steps to reproduce the behavior:

1. pip install -U jupyter-book
2. jupyter-book create mybookname
3. jupyter-book build mybookname

[jbeanland]

@chrisjsewell (I hope you’re the right person to tag) this seems to be fixed now from Tornado==6.1 and pyzmq==22.1.0 From cpython 3.8, ayncio changed the default eventloop and it basically broke Tornado. Their 6.1 release finally fixed that. I am able to successfully build a book using cpython 3.9 and jbook 0.12.1 using these dependency versions.

What docs/build steps/requirements would need to be updated to confirm/inform about this fix? here and here are the most obvious. Probably pin these versions in the setup.cfg? How does the CI work? does it do any automated windows testing?

[firasm]

For anyone that stumbles on to this and is looking for the fix, here is what worked:

pip uninstall jupyter-book
conda create -n workenv python=3.7
conda activate workenv
pip install jupyter-book

Description of what the steps above:

• uninstall jupyter-book (for some reason it has a dash on windows but no dash on macOS/linux!)
• create a new conda environment with python 3.7 (thanks @phaustin!)
• activate the env
• reinstall jupyter-book

I am not 100% sure uninstalling and reinstalling jupyter-book is necessary, but after it worked, I wasn’t going to touch it again!