The fourth beta of watchOS 9.1 has been released by Apple for developer testing.
The latest builds can be downloaded by developers taking part in the beta-testing program via the Apple Developer Center, or as an over-the-air update for any hardware that's already running the beta builds. Public beta versions of the releases generally arrive a short while after their developer counterparts, available through the Apple Beta Software Program website.
The fourth beta of watchOS 9.1 arrives after the previous betas from September 27, and the betas before that collection landed on September 20. The first landed on September 14 for iOS, tvOS, and watchOS.
The fourth watchOS 9.1 build number is 20S5063c, in place of 20S5055e.
Release notes for watchOS 9.1 do not indicate any new user-facing features. The update addresses bug fixes and other improvements.
Both AppleInsider and Apple itself strongly advise users don't install beta operating systems, or beta software in general, on to "mission-critical" or primary devices, as there is the chance of issues that could result in the loss of data. Testers should instead use secondary or non-essential hardware, and to make sure they have sufficient backups of their important data at all times.