Warning: 14.04 LTS to 16.04 LTS upgrades are problematic, and should
not be attempted by the average user. Please install a fresh copy of
16.04.2 instead. To prevent messages about upgrading, change
Prompt=lts with Prompt=normal or Prompt=never in the
/etc/update-manager/release-upgrades file. As always, make a thorough
backup of your data before upgrading.
See the 16.04.2 release announcement  and our Release Notes .