Sony might have taken a lot of heat for being so late to update its current flagship phone. But the manufacturer apparently isn't taking any chances when it comes to Android 5.1. New firmware has been certified for both the Sony Xperia Z3 and Sony Xperia Z3 Compact. The new firmware version is 23.2.A.0.278.
While the new firmware isn't explicitly listed as being Android 5.1, Sony Xperia Z3 and Sony Xperia Z3 Compact owners would be ecstatic to receive the next update so soon after Android 5.0.2 was pushed out for the two models. That took place on March 16th. As of now, the new firmware has been certified for the Xperia Z3 D6653 and Xperia Z3 Compact D5833 models only.
The Android 5.1 update brings longer battery life and improvements to the 64-bit ART compiler, which should allow apps to open faster. Other improvements will be seen in RAM management and system stability. Lost and stolen devices won't work until the owner types in his Google password, even if the phone is factory reset. And issues that users have had with the "Okay Google" phrase that initiates Google Voice Search are fixed with the update.
Keep in mind though that even if this new firmware is Android 5.1, there still could be other testing required before the latest and greatest Android build actually reaches the Sony Xperia Z3 and Sony Xperia Z3 Compact.