I have the same problem. After first reboot of the Oreo upgrade, there were constant error with something like "com.android.phone stopped working" and Android version was still 7.1. After another reboot, Android version was 8.0.0, but all contacts etc. had vanished. I was still logged in as myself, meaning my Google account, but the phone will not synch my contacts or calendar, these are empty.
Home or background buttons don't work anymore, I need to click back button until whatever app is in the foreground is closed to get to the home screen.
Notification pane settings or more arrow icons do nothing, I can only reach settings from the app menu.
I too need instructions to recover from the broken upgrade.
> After reboot there where a lot of errors to be clicked away.
That is not normal. If it happens again, please make a note with the exact error messages word for word, or make screen-shots for reference.
I suggest remove the SD memory card if any(*) and factory reset the phone.
Then set up the phone on your Google account but do not install more apps or configure the phone until it has updated the OS and the built-in apps.
* A defective or too slow memory card may introduce all sorts of errors.
It's just generic advice, but it's what I would do if in your shoes.
Please let us know how it goes?
I removed my SD card and did a factory reset like Hans suggested. After the reset, the phone still reported it was 8.0.0 but was able to sync my contacts and the home, background app and notification pane buttons and icons worked again. The phone downloaded and installed another 1.7 GB update without problems. Putting back the SD card the phone complains it's not compatible and needs to be put to "supported state", whatever that means, and the phone formatted the SD card.
i think it's clear that this should not be the correct behaviour. I had the same problem like
Can I force to do a new download of the Oreo image ? If so: How can i do this?