watchOS 5.1 (build 16R6591) is an official Apple over-the-air update for the Apple Watch Series 3 (42mm, LTE), released on 2018-10-30T17:21:33Z. The update package is 148.03 MB. This is a delta (partial) update that requires 5.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 765b847a9b82847308f0012e4daab40546d8c162.zip.