Start Up utility not recognizing USB boot disk

I'm trying to create a bootable USB. I followed the instructions as outlined:

https://support.apple.com/en-ca/HT201372

It appeared to create the bootable installer as per the instructions. However, when I try to select the new disk from the startup, it is not listed.

Here is what I see from the Start Up App. Also below is the the USB information.

Any suggestions?

(I'm on a Mac Mini 2014 with Mojave 10.14.5)

Thanks



Mac mini 2018 or later

Posted on Aug 11, 2019 11:56 AM

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Question marked as Top-ranking reply

Posted on Aug 11, 2019 1:11 PM

Bootable USBs do not show up in System Preferences> Startup Disk. What you need to do is restart the Mac, whilst it is restarting press and hold down the option/alt key until the Startup Manager screen appears, then you can select the USB press Return

your Mac will no restart to your bootable USB.

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6 replies

Aug 11, 2019 5:58 PM in response to TimMerc

I believe that I see your problem. You will have to Erase it and start over. Your Data Traveler G3 USB drive has to be formatted MacOS (Extended Journaled), which it appears to be. However, you need to use a GUID Partition Map scheme, not Master Boot Record. Try that and see if it works. It should show up in System Preferences/ Startup Disk. I just plugged my macOS 10.14.6 bootable USB installer in, and it showed up right away as a startup disk.

If you copy the command from the Apple Support Article, make sure to name the drive "MyVolume" (without the quotation marks). Open Terminal and paste the command in the Terminal window. Enter your administrative password. It will ask if you want to erase your USB drive. Hit the Y key on the keyboard and Enter. Give a little time to finish.


Aug 19, 2019 10:08 AM in response to TimMerc

Thanks Eau and fussymo.

Neither of those options worked.


With regards to formatting the usb drive as a GUID Partition Map scheme, that option does not exist. When use the disk utility, the partition options is greyed out:


In the format option, I only get the below selections:


Eau, when I try your suggestion, I still only see the internal drive as an option to start up, not the USB.


Any other suggestions?

Thanks!

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Start Up utility not recognizing USB boot disk

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