F38 Upgrade -- "Can't Open Blockdev" After Upgrade

[blenderfox]

I'm running a F36 installation on ext4 with LVM.

I decided to upgrade using https://docs.fedoraproject.org/en-US...ystem-upgrade/ to go to F38

I chose to go via the commandline steps using dnf so I could approve the import of gpg keys.

It went smoothly, no error other than on VirtualBox keys (but that's a known issue)

I rebooted, let the system upgrade happen then it rebooted again

This time it hung. I removed the `quiet` switch from the kernel startup switches so I could see the startup messages. Don't have a picture to hand, but the message was something like

Can't open blockdev /dev/mapper/fedora-root-localhost

EDIT: Have got a picture now


Now I recognised the blockdevice it mentioned as being the LVM volume for my main root partition, but I don't understand why it can't see it now, since it's an upgrade not a repartition (at least I hope the upgrade didn't repartition my drive...)

The upgrade did keep my previous kernel config setup so I can still boot into F36 (without the blockdev error), but all the dnf repos are now pointing to F38 instead of F36.

I've reimaged my device back to its preupgrade state, but I would like to know what happened and if it's possible to fix this before I try the upgrade again.

I could, I guess do a clean installation from scratch on F38 but that would mean I'd have to copy my files off my F36, onto an external drive, then copy them back on after the clean install.

Could anyone provide some guidance?

[hmmsjan]

It looks like a mistake by grub. Can you compare in either /boot/grub2/grub.cfg or in /boot/loader/entries the F36 and F38 files whether there is
root=/dev/mapper/fedora_localhost--live-root or root=mapper/fedora_localhost--live-root.
Anyhow, I'm pretty confident that if you correct the F38 "root=" parameter to be the same as the F36 "root=" the system will work.
The parameter should of course point to the real name of your lvm with the updated root.

[blenderfox]

It looks like a mistake by grub. Can you compare in either /boot/grub2/grub.cfg or in /boot/loader/entries the F36 and F38 files whether there is
root=/dev/mapper/fedora_localhost--live-root or root=mapper/fedora_localhost--live-root.
Anyhow, I'm pretty confident that if you correct the F38 "root=" parameter to be the same as the F36 "root=" the system will work.
The parameter should of course point to the real name of your lvm with the updated root.

Ah, very good spot, I didn't see the missing `/dev/` bit. I will check that the next time I do the upgrade

Should I file a bug somewhere for this?

[blenderfox]

Okay, I have managed to fix this.

After trying again, it looks like they fixed the issue with the blockdev -- that error no longer appears and the root value is indeed correct. It still got stuck loading -- but no kernel panic, just a hang at "Loading Linux..."


However, I noticed the generated config for F38 is missing the initrd line. For reference, here's the FC36 version


Since the F38 version didn't work, I booted into the F36 kernel and then regenerated the grub config

grub2-mkconfig -o /etc/grub2.cfg
grub2-mkconfig -o /etc/grub2-efi.cfg

That added the initrd line back in


And now it boots successfully into F38.