Can't start nvidia-driver-460 in Ubuntu 18.04 (GeForce MX230)

It’s the very same problem as in
https://forums.developer.nvidia.com/t/nvidia-smi-nvidia-smi-has-failed-because-it-couldn-t-communicate-with-the-nvidia-driver-make-sure/166240?u=generix
gcc was switched to an incompatible version but switching it back doesn’t rebuild the kernel module. Please keep an eye on that thread to undupe.