New firmware has been certified by the PTCRB for the Xperia Z3+ with build number 32.1.A.0.434. Yes, this is the Android 6.0 Marshmallow release and compares to current firmware version 28.0.A.8.272 (Android 5.0.2 Lollipop).
Perhaps, yesterday’s reported release date of 7 March is true after all. If this firmware is the official final release, then expect the same build number to appear on the Xperia Z5 series as well as the Xperia Z4 Tablet. We’ll keep you posted once we hear more.
Thanks Ariz and Haziq!