Apple has opened up the beta-testing process for macOS Catalina, offering developers the first build of the macOS 10.15.2 update to try out.
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.
Apple's macOS Catalina 10.15.2 makes changes to how it handles HTTP Strict protections, including making certain top-level domains like .dev and .app part of the Foundation URLSession and NSURLConnection HTTP Strict Transport Security preload list. Apple that use URLSession to visit a matching URL will always do so as https://, rather than the older and insecure http://, and never as cleartext.
The shift to macOS 10.15.2 arrives shortly after the release of macOS Catalina 10.15.1 on October 29, which itself underwent three cycles of beta testing before shipping. The update included changes ranging from support for the AirPods Pro and new emoji, to providing an opt-in option for Apple's program to review audio of Siri requests.
Apple has already restarted beta testing for its other main operating systems following their own releases, with the first betas of iOS 13.3, iPadOS 13.2, tvOS 13.3, and watchOS 6.11 issued on November 5.
Both AppleInsider and Apple strongly suggest users don't install beta software onto "mission-critical" or primary devices, due to the experimental nature of the software. Instead, the recommendation is to install betas onto secondary or non-essential devices, and to ensure there are sufficient backups of important data before making any major system changes.