watchOS 4.0 (build 15R5365a) is an official Apple over-the-air update for the Apple Watch Series 2 (42mm), released on 2017-08-22T16:58:41Z. The update package is 87.51 MB. This is a delta (partial) update that requires 4.0 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 66f26849d1d4cf8599645a8284f99618a35aee3d.zip.