While were try to bring all latest and greatest images/templates to our VPS services, you might still sometimes find a slightly outdated versions of OS Templates installed. It’s rather easy to upgrade the system and this KB shows step by step how to upgrade Fedora 21 to Fedora 23 using new DNF upgrade plugins (a recommended way to upgrade by Fedora Project).
yum update -y && restart
yum install dnf dnf-plugin-system-upgrade -y
dnf system-upgrade download –releasever=23 -y
dnf system-upgrade reboot
Once the system is restarted and you get your ping back, login to your new and updated Fedora 23. Note that it might take about 5 minutes for this restart to complete.
It’s time to get to know new DNF package manager.
More details about upgrade on Fedora Project Wiki.