watchOS 6.3.1 (build 17U224) is an official Apple over-the-air update for the Apple Watch Series 1 (38mm), released on 2026-02-02T18:44:13Z. The update package is 546.97 MB. This is a delta (partial) update that requires 6.1.2 already installed. This update is currently signed by Apple, so it can be applied from Settings › General › Software Update.

Payload file: 198767127caaa1779be75f209a85e39f222c5520.zip.