tvOS 12.3 (build 16M5129d) is an official Apple over-the-air update for the Apple TV 4 (2015), released on 2019-04-08T17:20:49Z. The update package is 125.3 MB. This is a delta (partial) update that requires 12.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 2e13b9c1ea476ae4bca9735437b1ac0523545e81.zip.