USB Catalina Installer Not Bootable

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Level 1

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USB Catalina Installer Not Bootable

I created a Catalina installer on a 32 GB USB stick. Trying to do a clean install of Catalina on my 2018 Mac mini that is currently running Mojave.

The problem I'm having is that the USB installer is not bootable. In System Preferences>Startup disk, it does not appear as a startup volume. I have recreated the USB Catalina installer 3 times to make sure I did it correctly. Once using the Terminal with instructions from 9to5Mac,

https://9to5mac.com/2019/06/27/how-to-create-a-bootable-macos-catalina-10-15-usb-install-drive-video/

and twice using Install Disk Creator https://macdaddy.io/install-disk-creator/. So I'm pretty sure I'm not doing it incorrectly.

I was thinking the problem might be the T2 security chip not allowing it to be a valid startup disk since it is an external drive. I started up holding Command-R and opened the Startup Security Utility and set it to Allow booting from external media.

I still can not startup from the new USB Catalina install disk. Any suggestions?

Gary

Mac mini, macOS 10.14

Posted on Jan 17, 2020 4:29 PM

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Answer 1

Top-ranking reply

fuzzymo

Level 4

2,036 points

Jan 18, 2020 8:08 AM in response to Gary Looft

Open Disk Utility. Click on "View," then "Show All Devices". Select your USB stick drive media, not the indented volume below it. It should show what type of partition scheme you are using. If it shows Master Boot Record, you will have to erase and reformat your USB stick as, Format: macOS Extended (Journaled) with Scheme: GUID Partition Map. Then you will be able to make your bootable installer.

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Answer 2

Jan 18, 2020 8:21 AM in response to Gary Looft

Gary Looft wrote:

I was thinking the problem might be the T2 security chip not allowing it to be a valid startup disk since it is an external drive. I started up holding Command-R and opened the Startup Security Utility and set it to Allow booting from external media.

I still can not startup from the new USB Catalina install disk. Any suggestions?

I suspect this is still your issue.

Verify your settings again—

then Try resetting NVRAM/PRAM http://support.apple.com/kb/ht1379

Try resetting the SMC https://support.apple.com/en-us/HT201295

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Answer 3

dialabrain

Level 10

124,925 points

Jan 17, 2020 5:37 PM in response to Gary Looft

As a test I created a USB Bootable installer using Apple's instructions…

How to create a bootable installer for macOS - Apple Support

It appears in Startup Disk on both a iMac Pro with a T2 chip and Macs without the T2 chip.

As mentioned, make sure the flash drive is formatted correctly.

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Answer 4

fuzzymo

Level 4

2,036 points

Jan 18, 2020 3:55 PM in response to Gary Looft

I usually use the method described here: How to create a bootable installer for macOS - Apple Support

Make sure to name your volume "MyVolume". This method has always worked for me.

Erase your USB drive and try again.

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Answer 5

Gary Looft Author

Level 1

15 points

Jan 18, 2020 12:49 PM in response to Gary Looft

I jumped the gun in saying this was solved...still can not start from the USB. Getting this error in System Preferences>Startup Disk.

"You can't change the startup disk to the selected disk. The bless tool was unable to set the current boot disk."

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Answer 6

Gary Looft Author

Level 1

15 points

Jan 19, 2020 11:00 AM in response to fuzzymo

I'm at a dead end. I was able to get the USB stick to appear to be bootable. I can select it when I startup holding Option key and select it but when I restart, the progress bar goes 3/4 of the way to the end, then starts over. When it starts up it is not in the Catalina installer, it is in Mojave restore. So still unable to start from it. I verified that Startup Security Utility is set to Allow again.

I zapped the PRAM. Control-Option-P-R.

Any other ideas.

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