Sony Xperia Z3+, Z4 and Z5 series get firmware update
Unfortunately for those who like exciting new features, this particular update is of the housekeeping variety. Once installed, you probably won't find anything new with the Marshmallow-based build, but this doesn't mean you should disregard it completely. If you care about security and prefer an overall experience with less potential hiccups, this firmware update is one you'll want to have on board.
As per the changelog, build 32.2.A.0.305 adds the following:
- The latest security enhancements included
- All of our latest bug fixes and improvements
- Audio volume enhanced in notifications and ringtones
- Improved handling of Bluetooth connected devices
The firmware update is worth installing for the Android security patches alone. The previous build was only updated as far as April's official Security Bulletin from Google, and many dozens of potential holes have been filled since then. It's intended for the Xperia Z3+, Z5, Z5 Premium, Z5 Compact and in all likelihood, the Z4 Tablet.
The update is rolling out over-the-air, so should reach your device shortly if it hasn't already.
source: Xperia Blog