Fedora 26 is out! As someone who can't stop tinkering and breaking things I've decided to upgrade my workstation (and see if dnf can handle the process without any major flaw).

So without further delay here are the steps I took (your mileage may vary):

If you're in doubt that your machine is compatible with Fedora 26 download the live image (here) and test it first. And again, don't forget to backup before starting the upgrade process! I like to use Clonezilla for that.
  1. Upgrade your current system to the latest available packages on Fedora 25:

Restart your machine now, especially if your kernel was updated with this command.

  1. Install the system upgrade plugin for dnf:
  1. Download the newest packages (Fedora 26):

I added the --exclude "synergy vagrant" because I'm using versions that are different from the ones available in the official repositories. You may ignore that. It's here for documentation purposes only.

  1. This is the final step. After this, if everything went well, you'll reboot into Fedora 26:

And it's done! Everything went right as it should and quite frankly, better than I expected. My system is working as good as before, and I haven't noticed any problem. Anyway, the official documentation for this process is here. You should read it.