This is a copy-paste of
https://forums.opensuse.org/t/boot-problem-after-15-5-tumbleweed-upgrade/167250

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After upgrading from Leap 15.5 to Tumbleweed, my system failed to boot with a
message:

No filesystem could mount root, tried:
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(8,2)

I think I’ve narrowed the problem down to dracut failing during the upgrade
process. The relevant lines of output are:

dracut-install: Failed to find module ‘atiixp’
dracut[E]: FAILED: /usr/lib/dracut/dracut-install -D
/var/tmp/dracut.X8M8eJ/initramfs -N ^i2o_scsi$ --kerneldir
/lib/modules/6.3.7-1-default/ -m pata_atiixp ata_generic fan atiixp
ide_pci_generic jbd ext3 edd
dracut[F]: installkernel failed in module suse-initrd

The /etc/sysconfig/kernel contains the line:

INITRD_MODULES=“pata_atiixp ata_generic processor fan ahci atiixp
ide_pci_generic jbd ext3 edd”
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There were stale entries in INITRD_MODULES which caused dracut to fail.

My enhancement suggestion is: 

1. If dracut fails during installation, state clearly that this leaves the
system in an unbootable state. This would help users who are not familiar with
the Linux boot process to understand what the problem is.

2. If dracut fails because of missing modules during installation, allow the
user to edit the INITRD_MODULES setting and trying dracut again.