Cannot update ubuntu kernel

[malomehi]

I tried a dual boot installation with Ubuntu and LibreELEC. They both boot ok and work.

The problem comes if I update Ubuntu kernel with apt-get, after doing that Ubuntu does not boot any more.

If multiboot kernel is used then Ubuntu kernel cannot be updated.

Any solution?

Updated: I realised this issue is not because of updating the kernel. First boot in Ubuntu after fresh installation is ok, but it will not boot again after reboot (even not doing any system update).