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Trying to make a bootable install drive for MacOS and to install I need to erase the disk, tried Disk Utility and it gives me an error saying unable to unmount disk and terminal cannot find a Sudo command to force unmount it, help please!
note that I am trying these terminal commands from MacOS recovery
MacBook Pro 13”, macOS 10.15
Open Disk Utility, click on View in the menubar and select Show All Devices.
Highlight the Disk, not any of the indented Volumes. Click Erase.
Give the disk a name,
Format: APFS (for High Sierra,Mojave or Catalina, MacOS Extended (Journaled) for other macOS's
Scheme: GUID Partition Map.
Click Erase.
What is on the Disk at the moment and what OS are you trying to install on it.
how is it connected to your mac, it needs to be connected directly, not through
any USB hub.
Open Disk Utility, click on View in the menubar and select Show All Devices.
Highlight the Disk, not any of the indented Volumes. Click Erase.
Give the disk a name,
Format: APFS (for High Sierra,Mojave or Catalina, MacOS Extended (Journaled) for other macOS's
Scheme: GUID Partition Map.
Click Erase.
What is on the Disk at the moment and what OS are you trying to install on it.
how is it connected to your mac, it needs to be connected directly, not through
any USB hub.
I have already tried that method in disk utility and as I said it failed to unmount the disk. Nothing is on the disk except for the MacOS Mojave installer and the disk is attached via a USB A to USB C adaptor.
Hope this helps!
Restart your mac and try it again, anytime I have come across a Disk that will not unmount
a Restart has sorted it out.
With the external disk connected open Terminal and type in
diskutil list
press Return
from the list make a note of disk identifier and then type
diskutil umount disk<whatever the identifier is, something like disk1s2>
press Return
this is just to see if it will unmount
to mount the disk again enter
diskutil mount disk?s?
press Return
if it unmounts and mounts then try Disk Utility again.
If there is only the macOS Mojave.app on the external then move it to your Desktop, erase it from the external drive, then simply double-click the Install macOS Mojave.app or whatever OS it is you
want on the external disk to start the installation process, go through the screens until you get to the section where you select which disk you want to install Mojave or whatever on.
Select the external disk.
FWIW, according to the OP the user is trying to create a bootable installer.
"Trying to make a bootable install drive for MacOS"
Also, according to the profile he/she is running Catalina. "Install macOS Mojave" won't run from Catalina.
The title suggests they want to install OS on the external drive, the body of the text mentions
bootable install drive, so could be construed both ways.
The OP has not indicated what OS he wants to install on the external,
and yeah you are right that as he is on Catalina if he tries the Mojave installer it will refuse.
I think we need more clarity from the OP as to their intentions.
They are called StrangePC, which over here in the UK could mean Strange Police Constable.
OOOh Matron!
Yeah I know but as the initial post is ambiguous.
If they do want Mojave on the external disk then making a bootable USB stick
installer would be the first stage, as per your link above.
Boot to the USB stick and install Mojave on the external drive that way.
Anyway let's see what happens.
I will try all your suggestions now, thanks for the advice. And since I’m booting from an external drive my Mac technically isn’t on a software so Mojave can run on the drive. Catalina refuses to open install MacOS Mojave but the drive just goes into recoveryOS and says I can install MacOS Mojave
Ok, well I used an app called macOS Mojave Patcher and now when I boot up from the drive, it looks like its telling me to turn on an external mouse and keyboard. Is there any way to use a internal? aka my Mac keyboard and trackpad? Thanks
This might be a hint. 😎
StrangePC wrote:
Nothing is on the disk except for the MacOS Mojave installer…
Thanks for all of your help again, I restarted my Mac and was able to unmount the disk. Now when I am trying to install the copy of MacOS it's saying "The Disk is Locked", any ideas now?
You can't run an installer for a macOS version lower than than the one you're using.
StrangePC wrote:
Ok, well I used an app called macOS Mojave Patcher…
FWIW, all bets are off when you use an unsupported hack.
Trying to install MacOS on a external drive
