tvOS 12.1.2 (build 16K534) is an official Apple over-the-air update for the Apple TV 4 (2015), released on 2019-01-22T18:13:59Z. The update package is 67.71 MB. This is a delta (partial) update that requires 12.1.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 8942955507d4810073aa932d7e1c605ccb1e2068.zip.