watchOS 5.3 (build 16U569) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm), released on 2019-07-22T19:17:47Z. The update package is 846.5 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: 3cd4ae33c7b41c022306643b3380dd3865797ab4.zip.