Recently I've tried to upgrade Ubuntu from version 14.04 to 16.04 and discovered that for some reason
sudo do-release-upgrade -d doesn't work as expected:
eax@fujitsu:~$ sudo do-release-upgrade -d
Checking for a new Ubuntu release
No new release found
There is little information about this issue in the Internet so I think this howto can really help someone.
First of all, go to System Settings -> Software & Updates -> Updates, make sure
trusty-updates checkboxes are selected. Run:
sudo apt-get update
sudo apt-get upgrade -V
sudo apt-get dist-upgrade -V
After reboot make sure your Ubuntu version is 14.04.4 now:
eax@fujitsu:/etc/apt$ cat /etc/lsb-release
DISTRIB_DESCRIPTION="Ubuntu 14.04.4 LTS"
eax@fujitsu:/etc/apt$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 14.04.4 LTS
Now edit /etc/update-manager/release-upgrades:
eax@fujitsu:~$ cat /etc/update-manager/release-upgrades
# Default behavior for the release upgrader.
Prompt=lts # <--- CHECK THIS LINE!
After all this
sudo do-release-upgrade -d should upgrade your system to 16.04.1 or newer.
Supplemental: Common issue after updating to 16.04 is a re-enabled guest login. To disable it just execute this command:
sudo sh -c 'printf "[SeatDefaults]\nallow-guest=false\n" > /etc/lightdm/lightdm.conf.d/50-no-guest.conf'