Just as the milestone beta process finishes, Apple starts the process once again, providing developers with the first builds of iOS 15.1, iPadOS 15.1, watchOS 8.1, and tvOS 15.1.
The newest builds can be downloaded via the Apple Developer Center for those enrolled into the test program, or via an over-the-air update on devices running the beta software. Public betas typically arrive within a few days of the developer versions, via the Apple Beta Software Program website.
The latest generation of builds arrives shortly after the public releases of iOS 15, iPadOS 15, watchOS 8, and tvOS 15 on September 20. GM candidates for the operating systems were issued on September 14, following after eight cycles of beta testing, nine for tvOS.
The first iOS and iPadOS 15.1 beta build has number 19B5042h, while tvOS 15.1 build 1 is 19J5542e, watchOS 8.1 beta build 1 is 19R5541f.
At this early stage, it is unknown exactly what Apple has included in the new betas, but they are likely to include improvements and fixes for issues in the initial iOS 15 release and comparative operating system updates. It is equally plausible that Apple is also preparing the next wave of feature additions post-launch.
AppleInsider, and Apple itself, strongly advise users avoid installing betas on to “mission-critical” or primary devices, due to the potential for data loss or other issues. It is instead recommended to install betas onto secondary or non-essential devices, and to ensure there are sufficient backups of important data beforehand.