What Does the ‘No Bootable Device’ Error Mean? The “No bootable device” error indicates that your Mac cannot find a valid bootable operating system to start up from. This typically happens when the macOS system files have become corrupted or the startup disk has failed in some way. Specifically, it means that your Mac attempted to boot from its designated startup disk, but was unable to … Continue reading What do I do when my Mac says no bootable device?