Jupyter ipywidgets v7.5 "Error displaying widget"

I have been using the dlinano build which I flashed to an SD card. I needed the fileupload widget … This is only available in v7.5 of ipywidgets … so I upgraded ipywidgets from version 7.4 as supplied to version 7.5.
I now get the error message “Error displaying widget” every time a widget command is used, including the supplied examples. Does anybody have any idea how to fix this? Other people mus be suffering this problem because if you do the standard upgrade every this you en up with this problem,

Self answered…
sudo -H pip3 install --upgrade jupyterlab

I had to upgrade jupyterlab to 1.2.4 … then fix the rest…

sudo -H jupyter labextension install @jupyter-widgets/jupyterlab-manager

The versions that worked were
jupyter core : 4.6.1
jupyter-notebook : 6.0.2
qtconsole : 4.5.1
ipython : 7.11.1
ipykernel : 5.1.3
jupyter client : 5.3.4
jupyter lab : 1.2.4
nbconvert : 5.6.1
ipywidgets : 7.5.1
nbformat : 5.0.3
traitlets : 5.0.0.dev