watchOS 4.2 (build 15S5090c) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm), released on 2017-11-06T18:03:48Z. The update package is 150.27 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: 3fa501124ec60857ffcc82d63573fc217f54ddea.zip.