watchOS 4.2 (build 15S5102b) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm), released on 2017-11-17T18:18:00Z. The update package is 63.04 MB. This is a delta (partial) update that requires 4.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 8a438a1afa29235a404765b9fa67ddca828d3d37.zip.