Question

How to Update Software of Sony Xperia Z?

Answer 1

The official update comes from Sony, you will be informed via a message that a new version of OS is ready and that you need to click on the Yes button

My advice would be to backup your smartphone before installing the update and to use a wifi connection, your mobile package might not be sufficient, usually the update of OS last for hours

Answer 2

1. Connect the phone to the computer using the USB cable.
2. On the computer, launch Sony PC Companion and it will automatically check for updates.
3. You'll be prompted if an update is available. ...
4. Click Accept.
5. Wait while the update is downloaded.