Apple releases watchOS 5 beta 10 to developersInstalling the watchOS 5 beta is more complex than an iOS or macOS beta, but it's also for developers only.
Of Apple's four primary operating systems (iOS, macOS, tvOS, and watchOS), only watchOS lacks a public beta, which isn't surprising, given how comparatively complicated is. You need to install a certificate on your Apple Watch, then download the software to your iPhone running the iOS 12 beta, transfer it across, and get it up and running. It's not hard, but it does take patience and you may have to troubleshoot.
How to download the watchOS 5 beta certificate
How to install watchOS 5 on your Apple Watch
How to downgrade to watchOS 5
What's new in the watchOS 5 beta?
August 31, 2018: Apple releases watchOS 5 beta 10 for developers
Apple has just released watchOS 5 beta 10 for developers. If you already have a previous watchOS 5 beta installed, proceed to the Watch app on your iPhone running iOS 12 and download away. If you were waiting to begin watchOS testing with version 5...
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Apple releases watchOS 5 beta 10 to developers