I'm trying to Upgrade Eclipse Neon to Oxygen on Windows 10.
I started Eclipse with Administrator privileges and then followed the instructions described in the Eclipse Wiki.
The upgrade runs without errors and prompts for a restart. After the restart, Oxygen comes up without errors and everything seems fine. But when I close Eclipse and start it again, it's back to Neon, duh.
Oh, how I miss Arch Linux's pacman...
I had the same problem. Every restart after the initial upgrade from Neon to Oxygen, I got a "Requirements Update" dialog that prompted me to downgrade some of my components from 4.7 to 4.6 after which point I was back on Neon. Oops. Apparently "Oomph" still thought I should be on Neon and was trying to "fix" things.
I followed the following step outlined here:
https://www.eclipse.org/forums/index.php/t/1082235/
open the Installation setup (Navigate -> Open Setup -> Installation) and in the properties view change the product version to say Oxygen
After I did this, Oomph left me on Oxygen after this.