There are plenty of disruptive ubuntu upgrade issues, for example for almost 5 years (through 12.04 to 16.04!) if you installed on LVM volumes your /boot partit

There are plenty of disruptive ubuntu upgrade issues, for example for almost 5 years (through 12.04 to 16.04!) if you installed on LVM volumes your /boot partition never cleaned up old vmlinuz and initrd images, causing dpkg-reconfigure to fail, leaving dpkg completely broken. Operating systems are hard.