Fedora 22 was released earlier this week, and if you are running Fedora 21, you will probably want to upgrade to the latest and greatest version of Fedora. Luckily, there is a tool called FedUp that is easiest way to upgrade to Fedora 22.
1. Make sure your current system is up-to-date and backed up
First up, ensure that you have the most up-to-date version of Fedora 21 by updating your system using the Software application, or running the following command in the terminal:
sudo dnf update
2. Install the FedUp tool
Now, open up a Terminal and install FedUp package by using the following command line:
sudo dnf install fedup
3. Start the update with FedUp
Now your system is fully up-to-date, start the upgrade using the following command:
sudo fedup --network 22
This command will tell FedUp to download all the appropriate packages from the Fedora repositories, and prep your system for the upgrade.
4. Reboot, and upgrade
Once the FedUp command from step 3 has completed without errors, reboot your system. In the Fedora Boot Menu (i.e. grub), there will be a menu item “System Upgrade”, select that and press enter.
All the appropriate packages and upgrade tasks will now be completed automatically, and when completed you will be able to start using your newly upgraded Fedora system.
For more detailed instructions on using FedUp for upgrading (including using a downloaded ISO or another installation source other than the network), check out the FedUp wikipage. This page also has details on issues that you may encounter during an upgrade.