watchOS 5.3.8 (build 16U680) is an official Apple over-the-air update for the Apple Watch Series 4 (44mm, LTE), released on 2020-07-15T17:28:41Z. The update package is 41.62 MB. This is a delta (partial) update that requires 5.3.7 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: e1ddb70cae51c4f0ec2ef186e742117b7fb3631a.zip.