Apple’s new M4-powered Macs are creating a buzz for their performance, but a hidden flaw is making some users reconsider the purchase. If you rely on virtualization software to run older versions of macOS, this might be a dealbreaker.

Reports, including detailed testing by Howard Oakley of The Eclectic Light Company, reveal that M4 Macs cannot virtualize macOS versions earlier than Ventura 13.4. Attempting to run a virtual machine (VM) with an older macOS results in a black screen, rendering the VM unusable. This issue does not affect earlier M-series chips like the M1, M2, or M3, which can virtualize macOS Monterey 12 and later without problems.

The root of the issue appears to lie in how Apple’s Virtualization API handles CPU cores during the VM kernel boot process. On the M4, the system seems unable to activate multiple CPU cores during the early kernel boot stage, which is critical for running these older systems. Even tweaking settings, such as allocating only a single core to the VM, hasn’t resolved the problem.

Adding to the frustration, there’s little hope for a fix. Addressing this would require Apple to update the kernels of older macOS versions—a move the company has rarely, if ever, undertaken. For users who need access to older macOS environments for legacy applications or testing, this limitation could severely hinder workflows.

What this means for buyers

If your work or hobbies rely on virtualizing older macOS versions, you might want to hold off on upgrading to an M4 Mac. Alternatively, consider retaining your current Mac or opting for an M3 model instead. For everyone else, the M4 Macs still deliver stellar performance and efficiency, making them a solid choice.

Apple has not yet acknowledged this issue publicly, and it remains unclear whether a solution will ever materialize. This development serves as a reminder that when it comes to cutting-edge hardware, progress sometimes leaves certain use cases behind.