Interpreting error screen in Jupyter notebook

I am running simulations in Jupyter notebook, suddenly I get this kind of screens:

Does anyone know what might be causing this?

This is all happening on Chrome on Ubuntu 18.

Maybe click on “learn more”?

Not very helpful, just generic chrome things how to solve it (reload the page, and that does work, but kinda irritating that it happens every 2nd time I run things, also interrupts the runs :frowning: )