Lagging a little behind the beta releases of iOS 11.4, tvOS 11.4, and watchOS 4.3.1, the first public beta of macOS High Sierra 10.13.5 was released by Apple today. A release exclusively for developers arrived last night.
Like the first iOS 11.4 beta, the initial 10.13.5 beta appears to restore support for Messages in iCloud, a feature that stores and instantly syncs the history of Messages apps used across multiple devices. The feature has intermittently appeared and disappeared in earlier iOS 11 betas since it was announced in June.
It’s also possible that 10.13.5 will include support for AirPlay 2, Apple’s updated audio and video streaming standard, which similarly reappeared in the iOS and tvOS 11.4 betas. AirPlay 2 promises to improve reliability of audio streaming between Apple devices, including the smart speaker HomePod, as well as enabling multiple HomePods to simultaneously perform together.
As a general statement, updating to Apple’s first public betas of any given OS release can be risky, as they can be particularly unstable and energy-inefficient. We don’t recommend updating to the beta release unless you’re using a backed up, non-production Mac that you can afford to leave somewhat unstable, and need the new version for app testing or similar purposes.
The new macOS 10.13.5 public and developer betas can be downloaded for free from the Mac App Store’s Updates tab. If you’re not a developer, registration with Apple’s Beta Software Program at the Apple Beta Software page is required to access the public beta version.