In case you are facing issues, while trying to update the Nokia’s Android homescreen launcher, Z Launcher, here is what you can do.
Go to your Android’s settings menu, go to the “Accounts” section. Select Z Launcher. In the screen that comes up, tap the 3 dots in the upper right to get to the account settings, and select “Remove account”
Go to settings -> Apps (or “Application Manager”). Select Z Launcher. Tap the “Clear data” button)
Go back to Z Launcher and run the update process again. It should now work properly.
This results in user data loss and you need to use Z Launcher again for sometime to make the predictions perfect.