watchOS 4.2 (build 15S102) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm), released on 2017-12-05T18:02:10Z. The update package is 151.19 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: 257847d002f639b24e05dcf140a7ff6f45844ae7.zip.