Level 1

115 points

Can't install macOS 15.4 on external volume

I am trying to install macOS Sequoia 15.4 on an external volume. The external volume is on an external drive and shares space with another volume. The drive is formatted APFS, GUI Partition Map and is connected to my Mac by USB 3 compliant USB "B" to "A" and USB "A" to "C" adapter. It is plugged into a Thunderbolt 4 port on the back of my Mac. My Mac is running 15.4.

I have tried various ideas but get the same end result:

the install is completed – it does a restart so I think it's complete;
the volume is locked;
the volume cannot be booted; and
so, the install process did not boot and enable a user account to be created.

I cannot find an installer log.

When the locked volume set as Startup Disk, there is an error "The version of macOS on the selected disk needs to be reinstalled.". When I try to run the installer again get another error: "This volume cannot be used since it has a secure token without any users. Please use Disk Utility to erase this volume.".

Things tried:

run installer from standard user account;
run installer from admin user account;
run installer from Recovery;
reduced startup security – have learned that is NOT necessary despite some Mac magazine articles;
toggled "Copy account settings from ....";
changed name of the Volume – took out space characters;
made sure the drive is NOT plugged into the DFU port.

Is installing on external volumes no longer possible ?

Mac Studio, macOS 15.4

Posted on Apr 8, 2025 9:35 PM

27 replies

Garry Brooke Author

Level 1

115 points

Apr 9, 2025 5:58 PM in response to Owl-53

It's a need to. I'm a developer and I am trying to replicate an issue with my applet experienced by a user who is currently booting from an external drive. Otherwise, I have sufficient backup facilities. Your comment about Apple Silicon needing a functional internal drive is correct. The macOS installer will only enable installation on an external drive if there is a functioning admin account on the internal drive. Yes, next I will try to install on an entire drive. I'll also test installing on a fixed size partition.

Garry Brooke Author

Level 1

115 points

Apr 9, 2025 10:39 PM in response to Garry Brooke

UPDATE: Tried to install on a partition on an external drive – failed in same way as before. The partition was in a separate container and so did not share space with the other volume. Will now try to install on an external drive with one container of one volume.

Garry Brooke Author

Level 1

115 points

Apr 10, 2025 3:55 AM in response to Ian R. Brown

Yes, that's my thought at present – I downloaded it from the App Store. A friend has another copy which has a different version, 20.3.04. I have been using version 20.4.02. I assume that there are changes which justify a different version number.

Garry Brooke Author

Level 1

115 points

Apr 11, 2025 9:28 PM in response to HWTech

Thanks. I did check that I was not using the DFU port. I chose an admin account during every install attempt. I had to enter the password for that account twice each time no matter how I invoked the installer. Don't think it's so bad I need to do a DFU revive or restore.

Apr 9, 2025 12:45 AM in response to Garry Brooke

See other discussions related to Sequoia installation, recovery or update.

Garry Brooke Author

Level 1

115 points

Apr 9, 2025 6:05 PM in response to Ian R. Brown

Thanks for the link to the video. As mentioned, the entire drive is formatted GUID Partition Map.

Apr 10, 2025 12:32 AM in response to Garry Brooke

Did you watch the first couple of minutes detailing formatting in the video I posted?

Follow it step by step.

It may be boring but boring usually gets the job done.

Apr 10, 2025 4:09 AM in response to Garry Brooke

My version is 20.4.02 and has worked OK on both the internal SSD and the external.

I always keep a copy because you never know when you will need it again and it cuts out the hassle of downloading.

Garry Brooke Author

Level 1

115 points

Apr 10, 2025 4:44 PM in response to Ian R. Brown

Ian, thanks. Yes, I did look at the video and I did format the entire drive in one experiment. Every time, I check that the entire drive is formatted GUI Partition Map. Cheers.

Garry Brooke Author

Level 1

115 points

Apr 12, 2025 6:01 PM in response to LuizAlvarez

Much the same happened to a friend recently trying to update a 15.3.2 install to 15.4 on an internal SSD. Lots and lots of errors and trouble.

s437885

Level 1

14 points

Apr 13, 2025 4:57 PM in response to LuizAlvarez

Same. Update borked my external boot setup.

Apr 11, 2025 11:23 AM in response to Garry Brooke

Make sure when you perform the install that the external drive is not connected to the USB-C port used for DFU Mode.....see the top section of the following Apple article:

Install macOS on an external storage device and use it as a startup disk - Apple Support

Also, when you went to install macOS onto the external volume, were you prompted to authenticate as a specific user/owner? If not, then that may be the problem.

It is also possible you may need to try a DFU Firmware Revive which resets the security enclave chip & system firmware and may help with "ownership" issues if the security enclave was having issues.

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Can't install macOS 15.4 on external volume