Hi @davidapl, sorry to hear about this.
Have you tried rebooting your phone in safe mode to see if you get the same error message there. Safe mode is a troubleshooting mode where all apps downloaded from Play Store is temporarily deactivated. That way you can see if this behaviour is caused by a downloaded app or not. For more information on safe mode and how to use it, click here.
If the same error message occurs in safe mode, my suggestion is to try to repair the software using a computer and Xperia Companion. Keep in mind though that a software repair will erase all user data from the phone, so make sure to do a backup of your user data before the repair.
Try this to begin with and feel free to keep me posted with the results!
