Level 1

19 points

Unable to boot from external USB media (M1 macbook pro)

Hello, I'm trying to install a copy of macOS Ventura on my external media (Samsung SSD T5) so I can have a separate bootable macOS to upgrade to the Sonoma beta for testing. I've done this before with my intel macbook pro without issues, but I can't figure out how to get it to work on the M1 macbook pro.

I've tried to install Ventura to the USB drive via the Ventura installer, and I've also tried installing Ventura to the USB drive from the recovery utility. Neither works. The USB SSD is set to GUID and formatted APFS

Whenever I try to set the USB Ventura as the boot disk, I get an error "Unable to set the startup disk." And when I try to select the USB disk from the boot options screen, I get a spinning wheel for a second then nothing. No message.

I've seen posts indicating that in the "Startup Security Utility" I need to allow boot media. This is NOT available on my M1 macbook pro. Though it is available on my intel macbook pro. How can I boot to macOS from external media? Surely this has been done on a mac with an Apple CPU?

Thanks

MacBook Pro 14″, macOS 13.4

Posted on Jun 11, 2023 7:20 PM

Top-ranking reply

Grant Bennet-Alder

Level 10

140,771 points

Posted on Jun 12, 2023 6:21 PM

<< Apple support told me that Apple CPU macs should allow booting from external drives by default >>

...then person you were talking to needs to be re-trained, because that is FALSE!

<< The Startup Security Utility on Apple CPU macs no longer has an option for allowing booting from external devices >>

That is also Not correct.

But it is not pushed in your face -- you must choose Startup Security Utility off the 'Utilities' Menu, as described in the article linked below, and unless/until you do, none of your alternate boot methods can work.

Change security settings on the startup disk of a Mac with Apple silicon - Apple Support

You must restart your Mac for the changes to take effect.

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Similar questions

22 replies

Apr 11, 2024 10:32 AM in response to Odysseus42

I have an external SSD with bootable and working version of macOS Ventura. My Mac is currently on macOS Sonoma 14.4.1. I don't remember when I installed Ventura on my external SSD, but I partition half of the disk for Ventura, and left half for another OS.

So now I am trying to install macOS Monterey on that other half. I have created a bootable installed on a separate USD-C stick and installation seemed to work fine. But now when I try to select macOS Monterey from the startup options I get the same problem as you described with the spinning wheel and then nothing when clicking 'Continue'.

However, when I try to use it as a startup disk I get a different error:

"The version of macOS on the selected disk needs to be reinstalled."

I have already reinstalled once but that didn't seem to fix anything.

Apr 11, 2024 11:22 AM in response to Odysseus42

Apple does not closely follow the problems posted on the forums. They can act only when a cohesive and fairly complete description of the problem is supplied. Many of these come in through Apple Support, but if you can supply a description of the issue, you can use product feedback to report this as a "bug report":

Product Feedback - Apple

Odysseus42 Author

Level 1

19 points

Apr 11, 2024 11:27 AM in response to Grant Bennet-Alder

Grant, I appreciate your enthusiasm in responding to posts on the Apple message boards, but if you could spend an extra minute to understand what is being posted, your responses might be more relevant to the discussion

Apr 11, 2024 12:58 PM in response to Odysseus42

<< Shame on Apple for this issue and not addressing it. >>

I heard you say something like, "this is a BUG, I hope Apple fixes it soon."

I encounter similar sentiments here in the forums every day. That is the part of your writing I was responding to. That is why I suggested you use the quick Product Feedback link. So many times, Apple does not even know something is a problem.

--------

I ALSO heard and internalized that your work-around was to make sure the name of the drive had no spaces, and it might also need to be 8-character short. If a similar issue comes up again, I am ready to suggest that work-around.

Apr 11, 2024 1:44 PM in response to maddin_io

Strangely enough, I also just installed macOS Sonoma on the same external drive on a separate volume and that boots just fine. Only macOS Monterey needed to be installed on a separate partition instead of a volume.

All my drive names have a space in them by the way.

Odysseus42 Author

Level 1

19 points

Jun 12, 2023 4:09 AM in response to kaz-k

Hi, yes, that is what I’m using

Jan 7, 2024 3:18 AM in response to Odysseus42

Odysseus- did you find a work around or solution to this issue? I'm in the same boat. I have no option to "allow boot media".

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Unable to boot from external USB media (M1 macbook pro)