Fedora contributor and Atomic engineer Dusty Mabe has written a complete set of upgrade instructions at the Project Atomic website.
Keep in mind that although the Fedora 26 Atomic Host continues to be updated, it is no longer regularly tested or formally released.
The Fedora 27 Workstation also has a graphical upgrade method.
Soon after release time, a notification appears to tell you an upgrade is available.
This will allow DNF to remove packages that may be blocking your system upgrade.
Once the previous command finishes downloading all of the upgrades, your system will be ready for rebooting.
Because the Atomic Host makes upgrades painless and low-risk (thanks to rollback), all Atomic Host users are recommended to upgrade to Fedora 27. These instructions assume you have sufficient space to rebase the new ostree.
First, add the remote for the Fedora 27 Atomic Host: You should see your Fedora 27 Atomic Host deployed.
To boot your system into the upgrade process, type the following command in a terminal: package, your system reboots into the current kernel installed for Fedora 27; this is normal.
Shortly after the kernel selection screen, your system begins the upgrade process. Once it finishes, your system will restart and you’ll be able to log in to your newly upgraded Fedora 28 system.