watchOS 5.1 (build 16R6591) is an official Apple over-the-air update for the Apple Watch Series 3 (42mm, LTE), released on 2018-10-30T17:21:32Z. The update package is 435.34 MB. This is a delta (partial) update that requires 5.0 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 115696c882b2f5449e88be88b31a6d54a7e87ba6.zip.