I upgraded from a USG & a Cloudkey Gen 2 to a Dream Machine Pro. After the migration I ran in to a problem that my APs were not being adopted. I ended up resetting my access points. I also had a problem removing the existing APs. I had to use the Ubiquit App on my phone to remove them. Still the UDM Pro was not adopting my APs after I reset them. Once I restarted the UDM Pro, the APs were adopted. I wonder if my original issue of the UDM-Pro not adopting the APs might have been resolved by restarting the UDM-Pro after the migration. So, if you run into a problem that your APs are not being adopted after the migration, restart the UDM-Pro a few times.

These were the steps I went through

1. First, update the new Ubiquiti router to the newest OS, Console, firmware, etc. Do this by connecting the new router’s WAN port to your network, connect a compute to the new router. Open a browser and go to 192.168.1.1, and set it up WITHOUT a cloud account.
2. After it is setup, now go to this address 192.168.1.1/network/default/settings/control-panel and install and upgrade everything you need. I had a problem updating the OS so I used the LDC panel on the UDM-Pro to update.
3. Once everything is updated reset the router to factory. I did this by inserting a paper clip in the reset hole in front of the UDM-Pro for 10 seconds. The LCD will show it is restarting.
4. Setting up new router.
   Disconnect your old router and the Cloud Key if you are using one.
5. connect your new router to your modem.
6. Don’t connect all your equipment yet to the new router. Connect one computer to the new router
7. Open the browser again and go to 192.168.1.1.
8. On the 1st screen at the bottom click “Restore From Backup”
9. Log in to your online account.
10. It will show available backup to choose from, choose one
11. Click next and restore will start
12. After your new router has restored from backup, you connect your LAN to it.
13. Your site manager will show the new and old Sites. You can delete the old one when you are ready.