Apple has released the sixth beta version of macOS High Sierra 10.13.4 to users participating in the Mac OS beta testing programs.
The new build of macOS 10.13.4 beta 6 arrives a business day after iOS 11.3 beta 6 was released for iPhone and iPad, and a new watchOS beta 6 build is available for Apple Watch beta testers as well.
MacOS High Sierra 10.13.4 beta 6 can be downloaded now from the Mac App Store Update section for users enrolled in the beta testing programs. Apple usually rolls out the developer beta first and soon follows up with the same version to public beta testers.
No major new features are expected in MacOS High Sierra 10.13.4, but the beta builds have been including support for iMessages in iCloud, along with the inclusion of the iMac Pro cloud burst wallpaper.
Presumably various bug fixes, security enhancements, and general improvements to the High Sierra release of the Mac operating system will be bundled as well.
The most recent final build of macOS 10.13 remains 10.13.3 Supplemental Update for High Sierra users.
It is widely expected that a final build of macOS 10.13.4 will launch alongside iOS 11.3, perhaps on or near an Apple education-themed event the company has scheduled for March 27. Previously, Apple had stated that iOS 11.3 would debut sometime this spring.
Looking beyond High Sierra, the next major version of macOS, assumed to be versioned as macOS 10.14, is likely to debut at WWDC 2018 on June 4 as a beta build. Apple usually unveils new system software in the early summer at the developer conference, and a final version becomes available to the public in the fall of the same year.