Volume ownership and Erase All Contents and Settings on macOS Sonoma

A colleague ran into a problem recently where they tried to run the Erase All Content and Settings (EACAS) function on an Apple Silicon Mac. Instead of erasing the Mac, instead the following error message was displayed.

Erase Assistant is not supported on this Mac

The error message was misleading however, because the Mac actually supported EACAS without a problem. The root problem was the user account which was logged in had the following characteristics:

• Had administrator rights
• Did not have volume ownership

macOS on Apple Silicon Macs includes a concept known as volume ownership. You must be a volume owner to perform the following tasks on an Apple Silicon Mac:

• Make changes to startup security policy for a specific install of macOS.*
• Be able to authorize the installation of macOS software updates or macOS upgrades.
• Authorize running Erase All Contents and Settings.

* There may be multiple installations of macOS on one Apple Silicon Mac; each macOS install would have their own startup security policy.

For more information on volume ownership, please see Apple’s Platform Deployment article linked below:

https://support.apple.com/guide/deployment/use-secure-and-bootstrap-tokens-dep24dbdcf9e/web (see the Volume ownership section.)

In this case, since the account in question did not have volume ownership, it couldn’t run EACAS. Fortunately for my colleague, there was another account on the Mac which did have the following characteristics:

• Had administrator rights
• Had volume ownership

Once they logged into that account and ran the EACAS function, this time EACAS worked fine and the Mac was successfully wiped.