watchOS 6.1 (build 17S5076a) is an official Apple over-the-air update for the Apple Watch Series 3 (42mm, LTE), released on 2019-10-16T17:12:59Z. The update package is 779.54 MB. This is a delta (partial) update that requires 5.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 31a164a0c3210fb6ac295eea71ef7e2492edcc06.zip.