@Rob23ik 

Take a look:

https://www.tp-link.com/en/support/download/omada-software-controller/

  @Rob23ik 

I just went through this.  You can literally take a backup from your current 5.x controller, then build the latest controller, quickly skip through all the initial setup stuff (just need to set the Admin login info and the device account if I recall along the way).  Once you get logged into the new controller, then just Restore your backup.  Once the Restore is applied, everything re-attaches to the new controller instance which now has all your configs moved over.  It was seamless. 

Full disclosure, I run my controller as a virtual machine (thanks to forum member mbentley) as a docker image.  If you're running on actual compute iron, then things can get a little messy if you need to upgrade the underlying dependencies like MongoDB.  If you have the CPU horsepower I'd highly recommend the docker approach (or other virtualization strategy), if you're running something like a Raspberry PI...then I'd build it all (base OS plus the Controller pieces) on a new flashcard because you can easily revert to the old one if things go south.

Note you can backup just the config, or the config plus up to 180d of logging data (I chose to preserve my data).  I stored the backup file to the laptop I was using to access the controller.