Hi Susana,
I assume you compiled Netgen from source? If so, the Python version does not matter, this is only relevant for prebuilt binaries for Windows and MacOS.
Did you follow the instructions here?
ngsolve.org/docu/latest/install/installlinux.html
To update the submodules properly, execute the following:
Code:
git submodule update --init --recursive || true
git submodule sync --recursive
git submodule update --init --recursive
Best,
Matthias