watchOS 4.0 (build 15R5365a) is an official Apple over-the-air update for the Apple Watch (42mm), released on 2017-08-22T16:58:30Z. The update package is 1.06 GB. This is a full OTA update that can be applied from any compatible base version. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: e8efda84b6a425012da945bd23bac1e40642d15d.zip.