sudo fedup --network 21 --product=nonproduct
Once Fedup completed
Reboot the system
Once the system reboots, there should be a new entry in the GRUB menu titled System Upgrade.
Select the System Upgrade option from the GRUB menu
Remark: If the System Upgrade item is not shown in the grublist at boot, it is most often caused by having a different grub, most often installed by another Linux distribution you may have in multiboot. To correct this quickly: reinstall grub:
grub2-mkconfig -o /boot/grub2/grub.cfg
grub2-install /dev/sda (replace /dev/sda by any other device you prefer to boot from)
The system should boot into the upgrade process and a plymouth boot screen should be displayed
There is a root shell on VT2 so you can tinker with the system if something goes wrong. (To disable this, boot with rd.upgrade.noshell)
Press 'esc' to see a more detailed log. If you switch back to the graphical progress indicator, it may show 0% for the remainder of the upgrade but that does not mean the upgrade has stopped.
Once the upgrade process has completed, the system will reboot and an option to boot Fedora 21 will be on the grub menu.
Cleaning Up Post Upgrade
It is worth rebuilding the RPM DB to prevent RPMDB checksum error when doing a distribution sync:
sudo rpm --rebuilddb
There are a collection of post-upgrade things to do. Some of which are fixed by doing a distro sync:
sudo yum distro-sync --setopt=deltarpm=0
This tool search for .rpmnew, .rpmsave and .rpmorig files and ask you what to do with them: Keep current version, place back old version, watch the diff or merge.
sudo yum install rpmconf
sudo rpmconf -a
If you are using google-chrome from the Google repository, you must re-install google-chrome due to a packaging bug on the Google side of things. Make sure to adjust the command to the build type you would like to install:
sudo yum remove google-chrome-\* && sudo yum install google-chrome-stable
Enjoy Fedora 21