watchOS 6.0 (build 17R5507l) is an official Apple over-the-air update for the Apple Watch Series 4 (40mm), released on 2019-06-17T17:12:18Z. The update package is 763 MB. This is a delta (partial) update that requires 5.1.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: c78cd9e7f63d068cdab2883830b0ba7c6ff7257d.zip.