watchOS 5.0 (build 16R364) is an official Apple over-the-air update for the Apple Watch Series 1 (42mm), released on 2018-09-12T19:18:45Z. The update package is 728.54 MB. This is a delta (partial) update that requires 4.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: cf0220927dcd104e2147adb247be2b6ab8eea9af.zip.