watchOS 6.3 (build 17U208) is an official Apple over-the-air update for the Apple Watch Series 1 (38mm), released on 2020-12-14T18:08:52Z. The update package is 170.18 MB. This is a delta (partial) update that requires 6.2.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: a7b8adf1a6b6633d607e7b549be57a24a6c6534f.zip.