watchOS 5.2.1 (build 16U5110a) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm), released on 2019-04-29T17:39:04Z. The update package is 467.81 MB. This is a delta (partial) update that requires 5.1.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 099407e52c9b5b180fe9f070fcc6e332fd005b6b.zip.