tvOS 12.1.2 (build 16K534) is an official Apple over-the-air update for the Apple TV 4 (2015), released on 2019-01-22T18:13:39Z. 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: 5851aced9e01b6e649dea1e6b9b704cb0520a2f3.zip.