Effort to reinstall OS on M1 fails when following Apple's published steps; even two Apple Sr. Advisors were stumped by the issue. One felt the computer needed to be returned and the problem could not be solved.

The following discussion came up in the context of trying to solve this issue.

Why do a clean install? @benwiggy argues pretty persuasively that you shouldn't

The separation of the OS on a read-only partition, with third-party installs and user-specific content all in different places means that there's very little point and usually an easier way to fix any problems. [...] Brand new hardware sometimes has special builds, that are a different fork from the available download.

My take on why

Clean install has been a great way in the past to remove all customizations and private information. It enables anyone to start from a known starting point shared by an entire community of users. I certainly think of it as 'best practice' when handing off computers between team members, and as a result I'm in the same boat.

Logical follow-on question: is there a better way of returning to "known starting point shared by an entire community of users", and/or of reaching a reasonable certainty that all private information is removed?

1 Answer 1


Certainly, if you are selling or passing on a Mac to someone else, then you should wipe the disk and install the OS anew, ideally leaving it so that it boots to the "Welcome" setup assistant. This will remove all personal data. (Trying to recover deleted data on SSDs is much harder than on hard drives.)

Cautious purchasers / recipients may wish to ensure that the computer is 'safe' by wiping the disk and installing the OS themselves.

But for the purposes of trouble-shooting an existing installation, or as part of 'routine maintenance', a clean install is largely 'overkill'. This is particularly true if you intend to restore most of your previous software and settings to the disk, leaving out only some elements that may be causing problems. It's analogous to destroying your whole house and rebuilding it just because you need to replace the toilet.

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