Cannot boot to macOS bootable USB installer

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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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Answer 1

Best reply

D.I. Johnson

Level 7

22,373 points

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

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Answer 2

hiiamaperson Author

Level 1

10 points

Mar 14, 2020 10:03 AM in response to Barney-15E

I have tried creating the installer 3 times now on 2 different USB drives with no luck. I am attempting to install macOS Mojave on this partition because I have games that will not run now that I have upgraded to Catalina.

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Answer 3

hiiamaperson Author

Level 1

10 points

Mar 14, 2020 9:15 AM in response to D.I. Johnson

Thank you for the advice. I redid the process of creating the bootable installer, but it still does not show up in the Startup Disk section of System Preferences. The disk was created with the macOS mojave installer.

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Answer 4

Barney-15E

Level 10

112,992 points

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.

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Cannot boot to macOS bootable USB installer

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