watchOS 6.3.1 (build 17U224) is an official Apple over-the-air update for the Apple Watch Series 1 (42mm), released on 2026-02-02T18:44:17Z. The update package is 518.45 MB. This is a delta (partial) update that requires 6.2 already installed. This update is currently signed by Apple, so it can be applied from Settings › General › Software Update.

Payload file: 354d46bef1b982a2d440d994b256107d1a14580e.zip.