Had to do this to get OTA update to Oreo
Settings>Apps. Under the three-dot menu in the upper right corner, select Show System. Then go to Google Service Frameworks, select Storage and Clear Data. Go back to System Update and Check for Updates. It will OTA update to Version 5.22A (not 5.220 as reported. I assume the A stands for Amazon version). No locked ads but the Amazon Icon shows up under Settings, right before G Google (Services & Preferences). I do not log in to Amazon and no Amazon apps are downloaded
Amazon build numbers starts from 00A0 rather than 00WW. "A" in 522A is just increment to 5220 adding Feb security update.
This method allowed me to download once but when I went to install it booted in recovery and didn't install. Subsequent attempts to deleate the google framework service storage data will not show the oreo update to download...
Worked perfectly. Thank you much for this posting. I am glad, that Nokia is hosting this forum, but disappointed that we need to resort to workarounds like this one instead of official instructions from Nokia.
Got the update today on my TA 1025 as well (without Amazon ads).
My device was previously stuck on the July 2017 security update so there's hope for us all. ^_^
I did a factory reset and oreo was waiting afterwards. This time it installed and all is well. It's just a pain setting up accounts, email & apps...