Apple’s most recent Macs utilize a new family of ‘Apple Silicon’ processors instead of utilizing Intel. As a result, these new Macs operate a bit differently in some key areas. Similar to T2 equipped Intel Macs, Apple Silicon Macs have a Startup Security Utility to control how disks are used as startup disks. While there is no option to allow or disallow external drives as startup disks, the settings require that the startup disk use either the currently signed operating system (similar to how iOS devices work), or a previously signed operating system. Previous methods of copying the operating system and then ‘blessing’ that system are no longer supported.

This means that any startup disk must have been created by an Apple macOS Installer. As a result, bootable clones, eDrives and Protogo devices as they previously functioned are not supported on Apple Silicon. This means that the eDrive and Protogo tools are not available on these Macs.

Currently, the best solution is to install macOS on an external drive and then install Techtool Pro. There are additional caveats, however. So far, the only drives that are 100% reliable as external startup disks are Thunderbolt 3 SSDs. USB 3 drives will sometimes work, but it is not yet clear how to make USB 3 drives reliable as external startup disks on Apple Silicon Macs.

To ameliorate some of these limitations, Volume Rebuild now supports live repair, and our development team is investigating other possible solutions to perform repairs from another disk.