watchOS 5.2.1 (build 16U5110a) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm), released on 2019-04-29T17:39:08Z. The update package is 190.17 MB. This is a delta (partial) update that requires 5.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 4c054370e3d67a0e9d9ca0f2b837e9e49a4849c9.zip.