watchOS 6.0 (build 17R5566a) is an official Apple over-the-air update for the Apple Watch Series 4 (44mm), released on 2019-08-15T17:18:42Z. The update package is 687.4 MB. This is a delta (partial) update that requires 5.2.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: d2f18675414e57819ca67d85306888eb09847aad.zip.