watchOS 5.0 (build 16R5283q) is an official Apple over-the-air update for the Apple Watch Series 1 (42mm), released on 2018-06-05T09:52:58Z. The update package is 545.84 MB. This is a delta (partial) update that requires 4.3.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 3759fcc63df95d8eccd3b041a4651a6f3ff5c016.zip.