It is supported to jump over one version, but not two.
This means, you can upgrade from 37 to 39, but not from 36 to 39. The latter should be done by upgrading first from 36 to 37 or 38, and then 39.
Hammerhead already mentioned the best page for the most reliable way of upgrading (especially if you want to jump over one version), but you might start to read that page from the beginning before doing the upgrade: Upgrading Fedora Using DNF System Plugin :: Fedora Docs
In accordance with the page, when it comes to the F36 that needs an F37 or F38 interim-upgrade before finally upgrading to F39, you just change the ... --releasever=39 line to …=37 or …=38 in the interim-upgrade in between F36 and F39.
A lot of vulnerable processes take place when you upgrade. Therefore, I suggest to focus on what is supported, and thus do not jumping over more than one release. Jumping over 1 (so, F37 to F39) is supported and equally tested as F38 to F39.
Be aware that you should always have the newest update state of your release before upgrading. This means, you should do in advance a normal update also on the F36 (e.g., dnf update or so) to ensure that it has the most up to date state that F36 had when it went end-of-life. This applies to all upgrades may it be with or without jumping over an release, and it applies to all releases, may they already end-of-life or not. This ensures that your upgrade process equals to the tested one.
Thanks to all for the replies, now I see clearly the situation. So is wise keep always the OS upgraded. Well because I work with VirtualBox the impact is not critical
If you don’t have to worry about production issues and data loss you can simply go to like 40 is current and get the rpm for fedora-gpg for 39 and upgrade your existing and then you can jump from any version newer than 22 I believe when they built the dnf upgrades. I just jumped from 33 to 40 and used a switch for cleaning anything that wasn’t compatible and it worked flawless. Mine is a home server I’ve had up probably 20 yrs from early fedora and been swapped motherboards drives and such and still is working. Now if they’d build this upgrade into Rocky then we’d be in a much better place. I understand the not supported but give an option to go outside the box on occasion.
You can upgrade in one or two version upgrades. But more is not recommended.
So you could do 36 to 38 to 40 but not 36 to 40.
Personally I go one by one and check for breakage before proceeding to the next version. In the rare case that something breaks I have found it easier to fix when there is a single version jump.
after each upgrade from version X to X+1 and periodically within a particular Fedora version. This helps you merge and deal with package upgrades having collisions with edited configuration files
This topic has been inactive for 9 months and it is solved (and related to f36 and f37) . It can be expected that this issue is no longer open. Also, the new posts seem to widely repeat the discussion of 9 months ago.
If anyone experiences an issue that is not solved by what has been posted so far, open a new topic. I close this one.