watchOS 5.3.1 (build 16U600) is an official Apple over-the-air update for the Apple Watch Series 2 (42mm), released on 2019-08-26T17:14:12Z. The update package is 828.12 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: 8be333da4085aa5235f82517335ec1fd814c9417.zip.