watchOS 6.0 (build 17R5566a) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm, LTE), released on 2019-08-15T17:17:31Z. The update package is 736.02 MB. This is a delta (partial) update that requires 5.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 643d0e485b471160786b2cf1349694fb0ceb4dbd.zip.