watchOS 5.0 (build 16R5303d) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm), released on 2018-06-19T17:36:52Z. The update package is 561.64 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: 54004bc19c2ab7324784ba26f67c07c8e1f291af.zip.