watchOS 6.3 (build 17U216) is an official Apple over-the-air update for the Apple Watch Series 3 (42mm), released on 2021-01-26T18:26:41Z. The update package is 601.11 MB. This is a delta (partial) update that requires 6.0 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 28838ed936a02585174530c199950a7fc02909cd.zip.