Error displaying widget: model not found (JupyterLab 3.4.4)

Dear @martinRenou and Team, sorry to bring this common issue up again, but I spent a whole day trying to figure out what is going wrong.

This is the code I run in my jupyter notebook (I am using a JupyterLab service built in our computational platform).

import sys
!{sys.executable} -m pip install ipyleaflet

from ipyleaflet import Map, basemaps, basemap_to_tiles

m = Map(
    basemap=basemap_to_tiles(basemaps.OpenStreetMap.Mapnik),
    center=(48.204793, 350.121558),
    zoom=3
    )
m

And I get this error: Error: Error displaying widget: model not found

In the browser logs I see: Error: Module jupyter-leaflet, semver range ^0.17 is not registered as a widget module (and some others)

The output of !jupyter labextension list is:

JupyterLab v3.4.4
/home/jovyan/.venv/share/jupyter/labextensions
        jupyterlab_pygments v0.2.2 enabled OK (python, jupyterlab_pygments)
        nbdime-jupyterlab v2.1.1 enabled OK
        jupyter-matplotlib v0.10.5 enabled OK
        ipyevents v2.0.1 enabled OK
        jupyterlab-plotly v5.7.0 enabled OK
        jupyter-leaflet v0.17.1 enabled OK
        @krassowski/jupyterlab-lsp v3.10.1 enabled OK (python, jupyterlab-lsp)
        @jupyterlab/latex v3.1.0 enabled OK (python, jupyterlab-latex)
        @jupyterlab/git v0.36.0 enabled OK (python, jupyterlab-git)
        @jupyter-widgets/jupyterlab-manager v3.1.0 enabled OK (python, jupyterlab_widgets)
        @voila-dashboards/jupyterlab-preview v2.1.5 enabled OK (python, voila)

Other labextensions (built into JupyterLab)
   app dir: /home/jovyan/.venv/share/jupyter/lab


The following source extensions are overshadowed by older prebuilt extensions:
    @jupyter-widgets/jupyterlab-manager

Do you see some extension as an obvious culprit?

[elisabettai]

Ooooooh, actually a hard refresh (of our JupyterLab service) fixed it.

Thanks a lot!

[martinRenou]

ipyleaflet is not part of the Docker image. I install it from inside the jupyterlab notebook with:

Ok. Just in case you didn’t do it, you will need to hard refresh your browser page to make sure to pull the latest JS extensions.