watchOS 6.0 (build 17R5507l) is an official Apple over-the-air update for the Apple Watch Series 4 (44mm), released on 2019-06-17T17:12:37Z. The update package is 656.74 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: b18c71216c589fcc8a2142a83d68cc2a9f50b8a1.zip.