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How to make a bootable Catalina installer?

My goal is to make a bootable Catalina installer on a USB drive, format my Mac, and start from scratch, but when I choose Catalina at the App store, screens look like it is going to start the actual install . . . but I'm not quite ready as I have a couple of apps that are not yet 64-bit compliant. Am I missing something?

MacBook Pro 15", macOS 10.14

Posted on Dec 21, 2019 7:02 AM

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Posted on Dec 22, 2019 4:06 PM

You can quit the installer if it launches—like any other app, command Q or from the dropdown menu>Quit.



It is nice to have a bootable USB installer—agreed.

You can boot off it, have access to Recovery, Disk Utility, a Terminal window and of course the installer.app itself.


Having a copy of the full installer sitting in the Application folder does not have that ability, particularly if you are in a triage situation—😉


How to create a bootable installer for macOS - Apple Support




3-2-1 Backup Strategy: three copies of your data, two different methods, and one offsite.


8 replies
Question marked as Top-ranking reply

Dec 22, 2019 4:06 PM in response to Tim Murray2

You can quit the installer if it launches—like any other app, command Q or from the dropdown menu>Quit.



It is nice to have a bootable USB installer—agreed.

You can boot off it, have access to Recovery, Disk Utility, a Terminal window and of course the installer.app itself.


Having a copy of the full installer sitting in the Application folder does not have that ability, particularly if you are in a triage situation—😉


How to create a bootable installer for macOS - Apple Support




3-2-1 Backup Strategy: three copies of your data, two different methods, and one offsite.


Dec 21, 2019 8:52 PM in response to LD150

peter_watt wrote:

And the installer need not be bootable. You copy it somewhere safe for future use then run it when needed.

It is better to create a new folder and move the installer to it. Then use Disk Utility to create a .dmg image of the folder & installer app. If you keep this installer on the system and start to download another installer macOS will not store the new download in the Applications folder, but will overwrite the previous copy no matter where it is stored on the drive. If the OP forgets the previous installer was moved, then the OP may not understand why the new installer isn't showing up in the Applications folder. It took me a while to discover the truth when it happened to me.

Dec 22, 2019 3:57 PM in response to LD150

Some people have multiple Macs where it might require a different macOS. If the other macOS is downloaded on this system because the other system cannot boot, then the previously stored installer will be overwritten. Some people also like to keep a specific revision of an OS handy as well. Apple has made it extremely difficult to download older versions of macOS so it is best to keep a spare copy around just in case.

Dec 23, 2019 12:51 PM in response to LD150

peter_watt wrote:

Interesting lists of hypotheticals the OP didn't request or mention.

I only brought it up in response to several of your posts which also were not prompted by the OP's original request. You implied moving the installer to somewhere safe would preserve it which I informed you is incorrect under certain circumstances. Plus if the user forgets about moving the installer and tries to download the installer again, the user will not find the new installer in the Applications folder as expected. The user is better off deleting the installer than moving it although archiving it is also an option to keep it safe as you were trying to suggest.


How to make a bootable Catalina installer?

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