tvOS 12.3 (build 16M153) is an official Apple over-the-air update for the Apple TV 4 (2015), released on 2019-05-13T17:20:34Z. The update package is 323.59 MB. This is a delta (partial) update that requires 12.1.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: a21362dbb13677b36f211ddcd2d27b2f318172d4.zip.