You might have read about the upgrade features, such as find my iPhone, and you are thinking about the upgrade. Be careful. A particular feature may cause you to waste time. Two-factor authentication is designed as an additional security measure but it may lead to you repeatedly entering your Apple Password numerous times on all of your devices.
The upgrade on the iPad Pro 9.7 inch started as all other upgrades; that is, I plugged in the device, and started the upgrade.
I went downstairs, fed the dog, cleaned the kitchen a bit, and upon my return saw the screen was hanging on Updating iCloud Settings.
I gathered up all the devices to see if something else was wrong but during the upgrade I had entered the passcode using the iPhone. No other device requested information.
Several rebooted attempts stopped the upgrade at different points: entering the WiFi password, entering the iCloud information, etc.
Disabled Two-Factor Authentication
Using my iMac, I finally browsed to the iCloud website and disabled the two-factor authentication for the account and restarted the iPad Pro. This time, I noticed there was an option to not enable the two-factor authentication.
Once the iPad Pro restarted then I was able to see the home screen but have been greeted with dozens of messages such as “Your Apple ID and phone number ….” This has happened on every single device.
Needless to state, after wasting 1 hour, I didn’t upgrade any of my other devices. I’ll wait.