watchOS 4.2 (build 15S5085b) is an official Apple over-the-air update for the Apple Watch Series 3 (42mm, LTE), released on 2017-10-30T22:07:37Z. The update package is 181.63 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: 3e9dfacfa0847cd237ea22f8ad62e43513c2dd1c.zip.