watchOS 4.2 (build 15S102) is an official Apple over-the-air update for the Apple Watch (42mm), released on 2017-12-05T18:00:57Z. The update package is 147.59 MB. This is a delta (partial) update that requires 4.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 999091af5584f1e81232d7a23f1566355c0ec2f6.zip.