In your case, did you just start Opera normally where you noticed that Opera had updated because the https://www.opera.com/client/upgraded tab opened or did you goto the URL opera://about to check for updates and click "Relaunch" after the update was ready? Sounds like the former from the title, but please clarify.
Also, look in Opera's install folder (path at the URL opera://about). What specific version folders are shown there? Curious to see if you were on the previous build before Opera updated or a build older than that (which would tell whether it was a small, patched update or a full download update).
Also, on your on Windows and if so, is your user account on Windows a limited/normal user account or an admin account?
Also, where is Opera installed? Is it in "C:\Users\yourusername\AppData\Local\Programs\Opera" or "C:\Program Files\Opera"?
Also, what install type does it show at the URL opera://about?
