How to upgrade OpenMediavault from 2x to 3.x?

You would be wise to make a disk image clone of your OMV 2.x disk and store that file somewhere safe.

If your upgrade fails, you can restore from the clone image and try again.

better is to do a new fresh install on a new boot media and configure services by hand, you spent some time, but none if compare to time spent to solve problems on upgrade.

PD: There are dozens of post of other users that do the same upgrade, please read it first to understand the problem.

eg: Upgrade 2.x - 3.x failed, config.xml broken?

Different strokes for different folks.

I had a very large time investment in building up my OMV 2.x machine over well more than a year since I started with it. It isn't just an OMV box, it does lots of other things for me and getting all that set up took a lot of time.

For me, installing OMV 3.x from scratch and rebuilding all the rest from scratch was not an option. If I could not upgrade OMV 2.x to 3.x I would have to stay on 2.x indefinitely. So far, there are no must have features in 3.x that would force me into it no matter how I got there.

In my upgrade attempts, and there were several needed, I cloned the 16GB SSD OMV 2.x system disk to another identical 16GB SSD. I then booted the clone and attempted the upgrade. After several attempts at this, trying different things, I was finally able to get a working upgrade.

What made the upgrade possible for me in the end was to uninstall all OMV plugins from the shell. Not just v 2.x plugins known not to upgrade to 3.x - all of them had to be removed. And removed from the shell, not the GUI, and removed but not purged.

Once I was booted into the upgraded to OMV, all I had to do was add the very few plugins back in and that was a fast and easy process.

Kinda pointless to say it in this case but: YMMV