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Cannot boot to macOS bootable USB installer

Hello,

I am attempting to install macOS on a separate partition on my late 2012 Mac Mini running Catalina version 10.15.3. I have successfully partitioned my drive and created a bootable installer on a USB disk, but I cannot boot to it. When I go to startup disk in system preferences the USB does not show up as an option. Pressing the option key on restart has no affect and does not bring up the startup disk menu. I reset the NVRAM as suggested on a different website but this has not fixed my issue. How can I get around this to boot to the USB?


Thanks in advance for the advice

Mac mini, macOS 10.15

Posted on Mar 14, 2020 6:51 AM

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Question marked as Top-ranking reply

Posted on Mar 14, 2020 8:00 AM

Insert the USB installer into a port on the mini.

Go to System Preferences > Startup Disk.

Select the USB drive as the startup and restart your Mac.


If the USB stick isn't recognized as a bootable system, then you'll have to redo the USB installer.


How to create a bootable installer for macOS - Apple Support



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4 replies
Question marked as Top-ranking reply

Mar 14, 2020 8:00 AM in response to hiiamaperson

Insert the USB installer into a port on the mini.

Go to System Preferences > Startup Disk.

Select the USB drive as the startup and restart your Mac.


If the USB stick isn't recognized as a bootable system, then you'll have to redo the USB installer.


How to create a bootable installer for macOS - Apple Support



Mar 14, 2020 9:21 AM in response to hiiamaperson

If the bootable installer doesn't show up in either place, it is not bootable. As D.I. Johnson noted, you'll have to try to create the installer again as it wasn't created correctly.


What OS are you attempting to install on the partition?

If you have a bootable system, just install from there.

Use DU to create a partition, then run the Catalina installer.

Cannot boot to macOS bootable USB installer

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