watchOS 4.2 (build 15S5085b) is an official Apple over-the-air update for the Apple Watch (42mm), released on 2017-10-30T22:06:58Z. The update package is 558.57 MB. This is a delta (partial) update that requires 3.2.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 9fb3c58ed243a0f746ba6d2703b001ce86ffa999.zip.