watchOS 5.2.1 (build 16U5110a) is an official Apple over-the-air update for the Apple Watch Series 4 (44mm), released on 2019-04-29T17:39:37Z. The update package is 471.37 MB. This is a delta (partial) update that requires 5.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: b8ffcbb02fb418e1727a3765495c5bd3036862f1.zip.