watchOS 5.3 (build 16U569) is an official Apple over-the-air update for the Apple Watch Series 1 (38mm), released on 2019-07-22T17:22:56Z. The update package is 854.49 MB. This is a delta (partial) update that requires 4.0 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 5933a09e14b5b31ca6107eab03062860c4c71e37.zip.