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Apple has reached the third round of developer betas in its current cycle, offering up new builds of iOS 12.3, tvOS 12.3, watchOS 5.2.1, and macOS 10.14.5 up for testing by program participants, as well as a second build for the third-generation Apple TV software version 7.3.
Developers taking part in the program can download the latest test build via the Apple Developer Center, or receive it as an over-the-air update on enrolled devices. Participants in the public Apple Beta Software Program can usually expect a similar beta update to be issued shortly after the developer version.
The third iOS 12.3 beta is build number 16F5139e, replacing the second build, 16F129d. Apple's third build of watchOS 5.2.1 is build number 16U5101c, up from the last version, 16U5091b. The new third build of tvOS 12.3 is build 16M5139a, taking over from the second build 16M5129d. Lastly, macOS 10.14.5's third beta, build 18F118d, increments from the second build, 18F108f.
The list of new builds also includes a second attempt at Apple TV Software 7.3, meant for the third-generation Apple TV. The latest build is number 12H833, replacing the initial build of 12H825 that arrived with the first builds of the other operating systems.
Both the iOS 12.3 and tvOS 12.3 betas feature a redesigned TV app, paving the way for the Apple TV Channels and Apple TV+ services, along with various changes to the Wallet app in preparation for the launch of Apple Card this summer. In the second beta, the app gained a new introduction screen, as well as the addition of new channels to the roster.
The third-generation Apple TV is also going to benefit from the new Apple TV+ and Channels experience, confirmed by the existence of new beta software releases for that device. Typically Apple does not issue new software for that model, instead preferring to update the fourth-generation Apple TV and Apple TV 4K, so producing new betas for it is an intention for Apple to bring its new services to as large an audience as possible, even those with legacy Apple hardware.
AppleInsider, and Apple itself, strongly recommend users don't install the betas on primary devices or hardware they deem as "mission critical" at all, as there is the highly remote possibility of data loss or other issues. Testers should instead install betas onto secondary or non-essential devices as a safer alternative, and to always make sure there are sufficient backups of important data before updating.