tvOS 12.3 (build 16M153) is an official Apple over-the-air update for the Apple TV 4 (2015), released on 2019-05-13T17:20:41Z. The update package is 134.93 MB. This is a delta (partial) update that requires 12.2.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 7e0325308b77d4caee92c160b9dec91255e75470.zip.