In the notes on the beta, Apple already highlights this error and recommends the terminal command “diskutil mount” in order to subsequently register the affected drives in the Finder. However, this did not work straight away for some users. Corentin Cras-Néneur indicated that only the order
sudo mount -t hfs [Laufwerkspfad]
led to success. He first determined the appropriate drive path using the “diskutil list” command.
A lot of “known issues”
Anyone who wants to try out macOS 26.4 in the beta version should be aware of the risks associated with it. Apple lists some unresolved issues that may occur in the developer trial version. M1 Macs could experience a kernel panic when booting from an external drive, Touch ID is unreliable in certain configurations, syncing calendars, reminders and notes with Exchange servers occasionally fails, and a few more. As always, beta versions should not be installed on productive systems, but should only be tried out on unnecessary test devices or in a virtual machine. This applies even more to an early developer beta.
Many innovations are coming
Apple has some significant innovations planned for the fourth major update of macOS Tahoe. The combined tab bar, which was withdrawn in the summer, returns for Safari. For the first time, laptop users can specify in detail the level to which their battery should be charged.

