watchOS 5.3.1 (build 16U6600) is an official Apple over-the-air update for the Apple Watch Series 2 (42mm), released on 2019-08-26T17:14:27Z. The update package is 116.64 MB. This is a delta (partial) update that requires 5.2.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 88d810cee0f92308e9a3bf4191f91368742b74dc.zip.