watchOS 6.3 (build 17U216) is an official Apple over-the-air update for the Apple Watch Series 4 (44mm), released on 2021-01-26T18:26:59Z. The update package is 69.85 MB. This is a delta (partial) update that requires 6.2.8 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: a21b2147bb0888befb3ce5c7c1c331021c30ed1f.zip.