IPython Notebook ipywidgets does not show

After googling for a while without hope, I realized that I need

jupyter labextension install @jupyter-widgets/jupyterlab-manager

Might have been a stupid mistake of mine, but in case you are using virtual environments, just keep properly in mind what is running from where.

You might properly run Jupyter from inside your current environment every time as needed, or might have a root env from which you always start the Jupyter you will end up using for all your environments.

For the latter case, what you need to be sure is to enable nbextension for the Jupyter you are actually running, instead of mistakenly run the command from within your currently active environment.

With the new version of ipywidgets, I ran into this problem, but then I found on their github readme that you now need to follow

pip install ipywidgets

with

jupyter nbextension enable --py widgetsnbextension

Note: To those using virtual environments (including conda environments) the recommended way to activate the extension is to run

jupyter nbextension enable --py --sys-prefix widgetsnbextension

That cleared the problem up for me.

If you've already got [an older version] of ipywidgets installed in Jupyter and you're seeing this problem (you'll probably be seeing javascript errors in the browser console) then you need to run the install command to update the relevant files e.g.:

jupyter nbextension install --user --py widgetsnbextension

And you may also need to rerun the enable command e.g.:

jupyter nbextension enable --user --py widgetsnbextension

Note: the --user argument may need to be different if you're using a virtualenv or other environment - see the ipywidget docs for more details.