watchOS 5.3 (build 16U6569) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm), released on 2019-07-22T19:18:35Z. The update package is 121.72 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: 8b0fcc4b27f39a880946baf79c220030d9e52fad.zip.