watchOS 5.1 (build 16R591) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm, LTE), released on 2018-10-30T17:21:20Z. The update package is 174.45 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: d96d84bc8d3aed2c7d29ebdba6bb70fb4ee1e33c.zip.