watchOS 6.3 (build 17U208) is an official Apple over-the-air update for the Apple Watch Series 1 (42mm), released on 2020-12-14T18:09:04Z. The update package is 200.72 MB. This is a delta (partial) update that requires 6.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: bb690d9646c06be0146af13ccc2aa0a2e519060d.zip.