watchOS 4.2 (build 15S5090c) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm, LTE), released on 2017-11-06T18:03:41Z. The update package is 78.02 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: ee8171525b81f5c74d8b98068def0ac26af2db2a.zip.