watchOS 4.2 (build 15S5090c) is an official Apple over-the-air update for the Apple Watch Series 2 (42mm), released on 2017-11-06T18:03:14Z. The update package is 70.25 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: 422f68f395c398c7510df1a7d67a8d12207f3377.zip.