tvOS 12.3 (build 16M153) is an official Apple over-the-air update for the Apple TV 4 (2015), released on 2019-05-13T17:19:28Z. The update package is 1.08 GB. This is a delta (partial) update that requires 9.2.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: cd929db1b5e242ba5db421a856a30103c474010d.zip.