watchOS 4.2.3 (build 15S600b) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm, LTE), released on 2018-02-19T21:17:48Z. The update package is 196.38 MB. This is a delta (partial) update that requires 4.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 929b08f0d13e7ed85d79e4edced9c00c4f3ef588.zip.