watchOS 4.2.3 (build 15S6600b) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm, LTE), released on 2018-02-19T21:17:49Z. The update package is 104.54 MB. This is a delta (partial) update that requires 4.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 1ce88e9c45c97031d0ee743156fb3570145c0063.zip.