watchOS 6.0 (build 17R5507l) is an official Apple over-the-air update for the Apple Watch Series 1 (38mm), released on 2019-06-17T17:11:16Z. The update package is 662 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: 0507dc57d6075014eb0bccc366363cf57b8ffe44.zip.