July 28, 2016, Ubuntu 15.10 (Wily Werewolf) has reached end of life for updates and support. There is no more updates, even for security fixes. Ubuntu 15.10 is not an LTS (Long Term Support) release and the life cycle is only 9 months (short life cycle support).
Ubuntu 15.10 was officially released on
October 22, 2015 and named as
Wily Werewolf as per Canonical naming procedure.
Whoever still running with Ubuntu 15.10, i know you have enjoyed a lot and lot of fun with your desktop. Everything one day come to an end so, don’t worry and run behind.
Every new release of Ubuntu comes with setup of fixes and improvement. To upgrading to latest one you will get more benefits on all the way, like software (You will get all the latest builds) & Better hardware support.
If you’re still using the Ubuntu 15.10 (Wily Werewolf), I’m strongly advising you to consider the Ubuntu 16.04 (LTS) Upgrade with immediate effort by today onwards.
Refer the following article for Ubuntu Upgrade from Ubuntu 15.10 to Ubuntu 16.04 LTS.