watchOS 5.2.1 (build 16U5079d) is an official Apple over-the-air update for the Apple Watch Series 2 (42mm), released on 2019-03-28T17:10:55Z. The update package is 442.9 MB. This is a delta (partial) update that requires 5.1.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 6e19df2bd2feaeecaa911d06e69c7ffe4a3cf836.zip.