tvOS 12.3 (build 16M5139a) is an official Apple over-the-air update for the Apple TV 4 (2015), released on 2019-04-22T17:08:27Z. The update package is 134.54 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: b3fb188049d3d7a25fcf32b97f9f97115914d88c.zip.