14 DAY TRIAL // At the request of our readers, we've created the following tutorial to teach all Ubuntu 15.04 (Vivid Vervet) users how to upgrade their installations to the Ubuntu 15.10 (Wily Werewolf) operating system.
In about two months from today, Canonical will no longer support the Ubuntu 15.04 operating system with software updates and security patches. The Vivid Verver series will reach end of life in January 2016.
Therefore, if you're using Ubuntu 15.04, it is highly recommended that you update your machines to the Ubuntu 15.10 release as soon as it becomes available on October 22, 2015. Most probably, you will receive an upgrade notification about it on your desktop.
To prepare for the upgrade, make sure that you have all the latest software updates released for Ubuntu 15.04 (Vivid Vervet). To do that, run the Software Updater utility from the Unity Dash, let it check for available update, and apply them all, if any.
Here's how to upgrade to Ubuntu 15.10 (Wily Werewolf)
If Ubuntu 15.10 has been officially released and you are lucky enough to see the upgrade notification, then everything is very simple. Just click the “Upgrade” button to proceed and wait for the tool to gather all the information needed to perform the upgrade.
At this point, you will be notified whether your computer is compatible with Ubuntu 15.10 or not, any third-party PPAs will be disabled during the upgrade process, which will take a few hours, depending on your Internet connection and the specs of your PC.
At some point, during the upgrade process, you'll be prompted with a notification that some obsolete packages will be removed, so click OK. Restart your computer when the upgrade process is complete. Congratulations, you've upgraded to Ubuntu 15.10 (Wily Werewolf).
Considering the fact that Ubuntu 15.10 is currently in Final Freeze and it will be released in three days from the moment of writing this article, you can force the upgrade process right now using the following command in the Terminal app.