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Cave Man

macrumors 604
Original poster
I'd like to do a clean install on a Mac mini M4 Pro from a USB-C thumb drive. I have the Sequoia 15.3 thumb drive ready, but I have not done this in several years. I know the new Macs have security chips build into them, so before I start I'd like to solicit advice from those of you who have done this. In the "old days" all one needed to do was to hold the "Option" key when turning on the Mac, then once the USB drive showed up, select it for boot, initialize the hard drive/SSD, then proceed with the install. Is this still the process on current Macs (in this case, Mac mini M4 Pro)?
 
I did that on my iMac M3 when my trackpad would not resolve the stuttering and jumping around. It was happening when I got the iMac New running Ventura and the self updated to Sonoma during setup. Sonoma helped but still did it occasionally. WORSE, Mail started to unexpectedly quit. I even did the reinstall Mac OS and Mail still kept quitting. So I did a clean install. No USB stick needed. Just do "Erase all contents and settings". It's the same as clean install. It fixed my Mail crashing and trackpad weird behavior also.

I forgot. I didn't do TM restore. I have iCloud sync and all that stuff came back. The Apps I redownloaded and set it up again. Then started a new TM backup after it was all set up again. I'm all Apple Ecosystem and services so it was easy to get back up and running.
 
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What version of the OS is on the Mini NOW?
Shoud be Sequoia, right?

WHY do you think a "clean install" will make any difference?

The easiest way to do this might be:
- backup your personal data, apps, etc. (time machine, SuperDuper, CarbonCopyCloner)
- use the "erase all content and settings" option to restore the Mini to "moment zero" (the moment you pressed the power on button for the first time).
- restore your data from the backup, either by using setup assistant, or put it back "by hand, one piece at a time" (the same way Johnny Cash built his Cadillac).
 
Thanks and yes I understand all that. But I want to know about a clean install for a USB thumb drive.

I agree with the previous posts about doing an Erase All Content and Settings. The SSV is deeply verified every boot and if it has one byte wrong the Mac will not boot. Have you got a particular problem you want to solve?

If you are determined to reinstall from the bootable USB, shut the machine down, plug in the USB. Reboot holding the power button down until you see “Loading startup options” then release. Then select the bootable USB and ‘continue’. The installer will launch. Quit the Installer and launch Disk Utility, erase the ‘Macintosh HD’ volume pair, create a new APFS volume, quit DU launch the installer, and point it at the volume you created. Do not erase the whole drive or you may delete the hidden volumes and the Mac will not boot. (You would need a second mac and Apple Configurator to restore).

After the installation finishes Setup Assistant will launch and you will have the opportunity to migrate in from your -Data volume backup, or proceed to set up from scratch, depending what you mean by “Clean Install”.

If you don't want to erase the Volume Pair you could just run the installer on top of existing. This will leave your -Data volume, so may not be a Clean Install to you.

You could do all the above equally well booted from Recovery, you don't need a bootable USB unless you want to install an older OS version.

PS Stricter ownership and security checks mean there are more things to go wrong doing these kind of operations on Silicon Macs compared to Intel, all avoided by Erase all Content and settings, and then restoring the -Data volume from backup with Migration Assistant, or proceeding to setup from scratch.
 
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Well, it sure is more complicated than it used to be.

The issue I'm having is there's some application that is causing instabilities. Not sure which one(s) but this all started after using Migration Assistant from my old Mac to move my home folder and Applications folder. I cannot eject any disks or thumb drives without the dreaded "in use" error message. Anytime I rename the computer in General > About, it seems to reset itself to the old name for some reason. I didn't transfer the settings to the new machine. Old machine was a 2014 mini running Monterey.
 
If you are determined to reinstall from the bootable USB, shut the machine down, plug in the USB. Reboot holding the power button down until you see “Loading startup options” then release. Then select the bootable USB and ‘continue’. The installer will launch. Quit the Installer and launch Disk Utility, erase the ‘Macintosh HD’ volume pair, create a new APFS volume, quit DU launch the installer, and point it at the volume you created. Do not erase the whole drive or you may delete the hidden volumes and the Mac will not boot. (You would need a second mac and Apple Configurator to restore).

Usually, when you Erase the Volume, the machine has to restart to complete the process before booting automatically back into macOS Recovery. It's best to power off the machine and boot it again from the USB stick before continuing.
 
Two thoughts, I have used Migration Assistant many times without problems, but I have always used it to migrate everything, not just Home folder and Applications. I don't know if what you did is a cause or not. The second thought is that 2014 Intel Monterey to 2025 M4 Mini is a big step. Many people would advise a fresh start, though maybe there are folks who have done it successfully.

I think you have three choices.....

1. Carry on from where you are and try to solve the two problems you mention.

2. Erase all Content and Settings and setup as a new Mac.

3. Erase all Content and Settings and migrate everything from the old Mac, if you still have it.

On solving the problems, the ejecting problem is very common and there is much discussion about it. This article may help: What to do when macOS won't let you unmount a volume. The commonest culprit for preventing unmounting is spotlight which can take a long time to finish big changes.

On the computer name issue you can change the name in Settings > General > About as you have, which has always worked for me, but you can also change it in the Settings > General > Sharing > Edit local hostname. Try doing it in both places and see if it sticks. If not I would start a new thread about it
 
Usually, when you Erase the Volume, the machine has to restart to complete the process before booting automatically back into macOS Recovery. It's best to power off the machine and boot it again from the USB stick before continuing.

I don't think I have seen this....after completing Erase all Content and Settings it has booted straight to Setup Assistant, though it may also show an activation screen before doing that. Steps 5 and 6 in the Apple article mentioned earlier.
 
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