I've found the solution on my 1320 Latin American CV:
The only customization you should do to your phone is to set it to your preferred language (in my case, US English). Then let it run all the updates from the app store undisturbed. Don't restart when prompted, only when done downloading and installing this first batch of updates.
Then run OS updates, restart as prompted. Run them again until no more updates are found. Then, if wanted, install the developer preview app and run THOSE OS updates.
Only once you've done all these things should you: change the clock format to 24 hrs if wanted, change any of the keyboard settings (adding or removing languages), change the calendar to start the week on Monday, and adjust the time settings to your liking. It's one of these three things that results in error something thing f8f. Once you have the OS up to date, you can change the clock format to 24 hrs, etc. If you already messed this up, you need to reset your phone and start over.