watchOS 5.2.1 (build 16U5091b) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm, LTE), released on 2019-04-08T17:12:43Z. The update package is 1.33 GB. This is a full OTA update that can be applied from any compatible base version. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: a272add6674778d34105e23676fb42cf0bafc366.zip.