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User profile for user: Stuart Field
Stuart Field Author
User level: Level 2
458 points

Cannot boot to Mojave bootable USB installer

I am trying to make a bootable USB drive installer for Mojave. I formatted the 16 GB drive using Mac Extended (Journaled) with a GUID partition. I created the drive in two ways, using the terminal commands given here, as well as by using the "Install Disk Creator" software package.


In either case, the drive does not show up when I restart and hold down the Option key, nor does it show up in System Preferences/Startup Disk.


After creating the bootable drive, the only file on the drive is "Install macOS Mojave." This file appears to be identical (exact same # of bytes) as the "Install macOS Mojave" app that I downloaded from Apple into my Applications folder, in other words, the process appears to have simply copied the installer. I would have thought that the process of creating a bootable drive would add a set of system and user folders to the drive as well.


In addition, I also used the same steps to try to create a bootable installation drive using a 500 GB hard drive, but it doesn't appear upon option/startup either.


Any further ideas?

MacBook

Posted on Dec 24, 2020 5:09 PM

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6 replies
User profile for user: Eau Rouge
Eau Rouge
User level: Level 8
42,608 points

Dec 25, 2020 3:56 AM in response to Stuart Field

Confirm your Install macOS Mojave.app is 6.05GBs in size and that it is in your Applications folder.



The USB stick you use should be 16GBs or greater in size and a named quality brand, I use SanDisk.

When reformatting the USB using Disk Utility have you selected the Show All Devices option

from View in the menubar.

The USB must be connected directly to the mac.

You then highlight the Disk and click Erase, not the indented Volume.

See the Screenshot below.





Once you have reformatted the USB stick you can then go onto create the bootable USB using the

Terminal command (copy and paste it into Terminal) for Mojave from this link,

How to create a bootable installer for macOS – Apple Support



The process will take about 20-30 minutes, wait till the Terminal prompt reappears.


When the USB has been created you can open it to a Finder window, you will only

see the Install macOS Mojave.app in a normal window, but if you have activated the

hidden folders you will see this. Press Shift - Command - .

that is the shift, command and the period/ full stop keys to see the hidden files and folders.



Go through all the steps again, just to make sure.


When booting from the bootable USB installer it must be connected directly to your mac,

not through any USB hub you may be using.


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User profile for user: Matti Haveri
Matti Haveri
User level: Level 6
16,895 points

Dec 25, 2020 1:31 AM in response to Stuart Field

No error messages when creating the USB installer device? Did you try to trash the old installer and re-download a new when connected via Ethernet? Is the installer file the "real" several GBs installer, not a tiny "stub" installer some macOS versions have? Try another USB flash drive? Shutdown, press-and-hold-Option while powering on?


Did you connect the USB installer device into the computer directly, not an USB hub?


Can that Mac run Mojave?

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User profile for user: Stuart Field
Stuart Field Author
User level: Level 2
458 points

Dec 25, 2020 12:44 PM in response to Eau Rouge

Thanks for the info. I do feel that I have followed these directions exactly. To Answer Matti's questions:


No error messages when creating the USB installer device? No errors.

Did you try to trash the old installer and re-download a new when connected via Ethernet? Yes, I tried that now.

Is the installer file the "real" several GBs installer, not a tiny "stub" installer some macOS versions have? Yes (6.05 GB)

Try another USB flash drive? Tried a hard disk drive as well.

Shutdown, press-and-hold-Option while powering on? Yes. Also, neither install drive appears in Startup Disks.

Did you connect the USB installer device into the computer directly, not an USB hub? Yes. Also with hard drive installer.

Can that Mac run Mojave? Yes, ran it for several years on this Mac.


I followed Eau Rouge's instructions exactly. I can see the system folders with Shift - Command - . Everything seems to be correct, except that neither the USB installer or the hard drive installer show up upon option-restart or in System Preferences/Startup Disk.


Is there any other test I can run to make sure my installer disks are properly formatted?





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Cannot boot to Mojave bootable USB installer

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