tvOS 12.3 (build 16M153) is an official Apple over-the-air update for the Apple TV 4 (2015), released on 2019-05-13T17:20:09Z. The update package is 774.17 MB. This is a delta (partial) update that requires 11.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 19386814ad2702c13d06631693b24fa69d5dd3bc.zip.