Am 16.09.21 um 18:55 schrieb Andrei Borzenkov:
The only similar error message in upstream grub is "kernel does not support 64-bit addressing"
Thanks! I now additionally have installed Ubuntu-64 16.04.1 without connection to the internet, to prevent from installing a newer GRUB version than from the install ISO medium. So now I have grub-efi-and64 in version 2.02~beta2-36ubuntu3.1 to boot with. With this version I'm able to boot Ubuntu-32 18.04.1 and Ubuntu-32 16.04.7 with a very recent kernel. So I still suspect, that the reason for my problem is the kernel version. -Ulf
