tvOS 12.3 (build 16M5146a) is an official Apple over-the-air update for the Apple TV 4 (2015), released on 2019-04-29T17:44:36Z. The update package is 135.32 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: 4064170b17d3f52e88bd0d5b793738cca4b66dc6.zip.