Apple’s first macOS 27 developer beta appears to introduce a serious issue for users who run multiple operating systems on their Apple Silicon Macs. According to reports from the Asahi Linux project and independent testing, macOS 27 Golden Gate can prevent Linux installations and some secondary macOS installations from appearing in the Startup Disk menu and boot picker.
While this bug is unlikely to affect most Mac users, it could create major headaches for developers, power users, and anyone who relies on dual-boot configurations. The good news is that the affected partitions and data remain intact. The issue appears to be limited to how macOS 27 detects bootable operating systems.
Asahi Linux issued a warning shortly after the release of the first macOS 27 developer beta, advising users not to upgrade if they currently use Linux alongside macOS on an Apple Silicon Mac. After updating to macOS 27, users may find that their Linux partition no longer appears as a bootable option in Startup Disk or the boot picker.
The problem is not limited to Asahi Linux. Early testing suggests that some Macs running older macOS versions on separate partitions can experience similar issues. This points to a broader regression affecting multi-boot setups rather than a Linux-specific change.
The root of the problem lies in how Apple Silicon handles boot selection. Unlike traditional PCs, the boot picker on Apple Silicon Macs is not a firmware-level utility. Instead, it is a macOS application that runs within the recovery environment of the default startup volume. If Apple changes how that software detects valid operating systems, previously supported boot volumes can disappear from the selection menu.
According to the Asahi Linux team, macOS 27 changes how the boot picker and Startup Disk app identify valid bootable partitions. As a result, existing Linux installations remain on the drive but are no longer detected correctly by the system.
Users who have already upgraded to macOS 27 may still be able to regain access to their Linux installation. If a separate installation of macOS 26 or an older version is available, setting that version as the default Startup Disk can restore visibility of the Linux partition. Once the older recovery environment is active, the boot picker should once again recognize the installation.
Asahi Linux has already patched its installer to prevent new installations from running under macOS 27 while the issue is investigated. The project has also filed a bug report with Apple and believes the behavior is unintended.
Since this issue was discovered in the very first macOS 27 developer beta, there is a strong chance Apple will address it in a future beta update before the operating system launches publicly later this year. macOS 27 is still in the earliest stages of testing, and significant changes are expected over the coming months.
For now, the advice is simple. If you use Asahi Linux or maintain a dual-boot setup on an Apple Silicon Mac, avoid installing the macOS 27 developer beta on your primary startup volume. Waiting for additional beta releases could save you from losing access to secondary operating systems until Apple delivers a fix.
