I don't want to upgrade to the new release, and I don't want to have the notification icon about the upgrade (red triangle with exclamation mark in it) sit on the tray constantly.
Ubuntu – How to make update manager stop nagging about a new release
update-managerupgrade
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Open the /etc/update-manager/release-upgrades with your favorite text editor, ie:
sudo nano /etc/update-manager/release-upgrades
Change the Prompt= line from Prompt=foo_setting to Prompt=never.
If you want a graphical way of doing it open the Ubuntu Software Center and under Edit > Software Sources > Updates you will find a Notify me of a new Ubuntu version option, from the drop box select Never.
If you're not getting an option to upgrade then your local mirror might be out of date, you can either wait a bit for that to resolve itself, or manually switch to another mirror. You should also make sure your software properties settings are correct.
After that follow the upgrade instructions:
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