watchOS 4.2.3 (build 15S600b) is an official Apple over-the-air update for the Apple Watch Series 2 (42mm), released on 2018-02-19T21:17:29Z. The update package is 573.51 MB. This is a delta (partial) update that requires 3.2.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 67ef1e4ae8fcb7e18f86cafd2d42f82a6027955e.zip.