Noting down this mainly for self reference since it occurred to me time and again, in case it helps others too.
I have several recent versions of LV installed on Ubuntu 20.04 (with alien). The nice thing is that somehow a NI deb package stream became known to the system, and some package upgrades are found automatically. However there is one caveat: each time the kernel is upgraded, several NI dkms kernel modules need to be recompiled. Usually that is automatically done, but sometimes stumbles on a missing config/modversions.h file. It seems that not every kernel headers package includes it. Missing that, LV crashes as soon as anything needing one such modules is loaded. E.g., as an easy test occurrence, when putting a new VISA control on an empty FP.
The solution is trivial: if the (usually empty) file is missing, create it with
sudo touch /usr/src/linux-headers-XX.YY.ZZ-generic/include/config/modversions.h
where XX.YY.ZZ is the kernel du jour version (e.g. 5.13.0-28 as of today).
sudo apt reinstall ni-kal
and a reboot then fix the crash.