watchOS 5.3 (build 16U569) is an official Apple over-the-air update for the Apple Watch Series 3 (42mm, LTE), released on 2019-07-22T19:17:10Z. The update package is 141.01 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: b73bc09aed8c860f71d1a77813a47d039e5483c0.zip.