watchOS 4.2 (build 15S5090c) is an official Apple over-the-air update for the Apple Watch Series 1 (42mm), released on 2017-11-06T18:03:36Z. The update package is 158.95 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: 18b5e0f285b86fc18a02d63c8d1bf7378b25a791.zip.