As you may know, our policy is to support stable releases for 18 months; Mageia 4 was released on February 1st, 2014, so it should have been supported until August 1st, 2015.
However, due to the delayed release of Mageia 5, we chose to extend the support period of our previous release to give you more time to upgrade your systems.
That brought the new end-of-life (EOL) date for Mageia 4 to September 19th, 2015, i.e. 3 months after the release of Mageia 5.
As we are now very close to this date, we wanted to give you a heads-up in case you haven’t done the upgrade yet: after September 19th, Mageia 4 will not receive any new security or bugfix update, so you are encouraged to do the upgrade as soon as possible.
Most users who did the upgrade had a smooth experience, just make sure to check the wiki to see how to do it. Feel free to ask for help on IRC, the forums or the mailing list if you need further guidance to upgrade to Mageia 5.