Along with iOS 11.2 Developer Beta 4 Apple released watchOS 4.2 Beta 4 for developers on Friday. watchOS 4.2’s big feature is Apple Pay Cash support, and it includes bug fixes, too.
Apple offers watchOS betas only to members of its paid developer program. If that’s you, and you already installed the provisioning file, you can install the update by launching the Watch app on your iPhone and going to My Watch > General > Software Update.