Welcome to the forum!
Lysia is already old. There was Kyria after that, and right now we’re on Mikah, and you’re bound to run into upgrade problems once you get Lysia up and running, because a lot has changed in the meantime.
Packages are now compressed with
zstd instead of
xz, and there have also been other major changes that could cause you to run into difficulties. For instance, GRUB was patched against the infamous Boot Hole vulnerability ─ which requires you to reinstall GRUB to the MBR or EFI system partition, depending on your setup ─ and now there has just been a serious upgrade to the PAM security system, which also brings its own set of problems to the table for certain users.
But that all said, your problem appears to be that GRUB cannot find the root filesystem. There could be multiple reasons for that, depending on what machine you’re on, how many drives there are, what partition table you’ve got, and so on. And ─ no offense, but I just have to say this ─ like most newbies to this forum, you seem to be under the impression that we have a crystal ball. I wish we did, but no, we don’t.
Best advice I can give you right now ─ and then I’m not getting into all of the difficulties I’ve mentioned higher up regarding the fact that your install
.iso is outdated ─ is to boot up from the USB key in live mode and check the
UUID of your root partition, and then compare that to what GRUB expects.
You can use the
manjaro-chroot tool on the live medium to autodetect your Manjaro root filesystem, and then
chroot into it, so that you can more easily edit
/etc/default/grub with the correct
UUID for your root filesystem ─ as well as
/etc/fstab ─ and then run
update-grub against the correct GRUB installation, because if you also have Mint on that system, then that will have its own GRUB, and you don’t want to update that one.
I’m afraid that’s as much as I can tell you with the scant information you’ve provided us with.