watchOS 5.0 (build 16R364) is an official Apple over-the-air update for the Apple Watch Series 1 (38mm), released on 2018-09-12T19:18:27Z. The update package is 762.31 MB. This is a delta (partial) update that requires 4.0 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: ea4174080e24d4c37315622a42ffd2ff2c1195e3.zip.