I just finished going through the upgrade to 22.04, as prompted by the OS (since security updates will be discontinued in a couple of weeks). The upgrade completed successfully, & prompted me to reboot. But after a reboot...the system fails to startup.

If I just let it boot the new default "Neon GNU/Linux" entry it added to the top of the grub menu, it stops saying "Gave up waiting for root file system device. Common problems: [...]," with a line at the bottom "ALERT! UUID=xxxx does not exist. Dropping to a shell!"

If I reboot & manually select the grub menu item I was previously using, kernel 5.15.0-53, it just stops at a BusyBox prompt with no error or information.

Not sure why the upgrade would hose my system like this....?