watchOS 6.3.1 (build 17U224) is an official Apple over-the-air update for the Apple Watch Series 4 (44mm), released on 2026-02-02T18:44:35Z. The update package is 651.06 MB. This is a delta (partial) update that requires 6.0.1 already installed. This update is currently signed by Apple, so it can be applied from Settings › General › Software Update.

Payload file: b15dfebccc482c27c95bcc7deb74d7c28c46ce54.zip.