watchOS 5.2.1 (build 16U5091b) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm), released on 2019-04-08T17:12:47Z. The update package is 476.45 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: a41cdaaecf978a2007ad5f01b6540979269bfa86.zip.