watchOS 5.1 (build 16R591) is an official Apple over-the-air update for the Apple Watch Series 3 (42mm, LTE), released on 2018-10-30T17:21:29Z. The update package is 778.92 MB. This is a delta (partial) update that requires 4.3.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 716ff1fc0111826ac45a0bfb51fe24512877c5e4.zip.