dnf is an amazing packaging tool in my opinion. And so far i had no problem to upgrade my system. This time, though, i tried an upgrade 3 distribution away. Fedora documentation ofcourse warns you that this might come with risks. Anyway i decided to give it a go and that ends with a problem in the booting process. While the upgrade finished smoothly without serious problems when i restarted i faced the bootloader which had the new kernel, the last two from Fedora28 and a rescue mode option. No matters where you chose to boot in, the loader was looping displaying the boot menu again and again.
To solve this, here what you can do
Press C to open the grub console and type
dnf save the old configs with the extension rpmsave. This is the old grub.cfg and with the command above you will be able to boot in the old distribution. From there the solution is to reinstall the grub with
/dev/sda is the boot partition. In case you wonder which one is yours use lsblk.
To solve this, here what you can do
Press C to open the grub console and type
configfile /grub2/grub.cfg.rpmsave
dnf save the old configs with the extension rpmsave. This is the old grub.cfg and with the command above you will be able to boot in the old distribution. From there the solution is to reinstall the grub with
grub2-install /dev/sda
/dev/sda is the boot partition. In case you wonder which one is yours use lsblk.
