watchOS 6.0 (build 17R5507l) is an official Apple over-the-air update for the Apple Watch Series 3 (42mm, LTE), released on 2019-06-17T17:11:54Z. The update package is 717.7 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: 22fefcfb5446e081893b875fe228b54d26c99bfe.zip.