Comment # 14 on bug 1051354 from Thomas Blume

(In reply to Fran�ois Valenduc from comment #13)
> I don't get a shell even with rd.shell. After the errors about the disks not
> found, I get this:
> 
> "Failed to start dracut-emergency.service: transaction is destructive
> Not all disks have been found
> You might want to regenerate your initramfs"
> 
> But initramfs images were already rebuild after update of udev.

This is bad, without a shell it will be harder to debug.
Can you boot with the parameter:

rd.break=initqueue

and see whether this gives you a shell?
If so, please attach the output of:

systemctl status systemd-udevd.service
systemctl list-jobs
journalctl -axb

if not, please boot with the additional options:

debug rd.systemd.unit=sysinit.target

and check whether you see something like:

Started udev Kernel Device Manager

if you see an error instead, please attach the error message.