How to Create macOS Catalina ISO DMG file?

The Lamehacker, a software developer and creator, developed a method by which you can easily turn a macOS app into a bootable DMG. He performed this method on macOS 10.14 Mojave, and he published this method on his profile on Github. The author called it ” macOS Mojave ISO creator” and published it under the GNU General Public License v3.0 license in September 2018.

Later this year, John the CEO and Founder of techsviewer.com, performed it upon the macOS 10.15 Catalina. And Certainly, t worked 100%. So, now you can use it easily to create a macOS Catalina ISO and DMG file.

If you are running macOS 10.15 Catalina on Virtual machine (VMware and VirtualBox) on windows, you can perform this method there too.

How to Create macOS Catalina DMG File?

Step 1. Download the macOS Catalina From App STore

The very first thing you have to do is to download the macOS 10.15 Catalina from the App Store. [If you are a windows user, then you must be thinking to download it on windows using IDM. So, don’t ever think about it because it won’t work.]

Once the macOS 10.15 Catalina is downloaded from App Store, it will be added to the Application. There you know that it is not a dmg and nor an ISO file. So, to make it a DMG file you have to go through some process to make them DMG or an ISO File.

Step 2. Open the Terminal and Follow the Steps

Before getting started with the process of creating a DMG and an ISO File, make sure, your PC has at least 10 GB of storage, so it should avoid unexpected errors.
First, You have to create an 8.681640625 GB DMG file, in other words, it will be 8900 MB. To do that, type the following command.

hdiutil create -o /tmp/Catalina -size 8900m -volname Catalina -layout SPUD -fs HFS+J

Now mount the created dmg file using the below command.

hdiutil attach /tmp/Catalina.dmg -noverify -mountpoint /Volumes/Catalina

Here you are about to change the DMG file to an Installer using the following command.

sudo /Applications/Install\ macOS\ Catalina.app/Contents/Resources/createinstallmedia --volume /Volumes/Catalina --nointeraction

 

Now you have to unmount the create Installer.

hdiutil detach /volumes/Install\ macOS\ Catalina\

That’s all How you can create a Bootable macOS 10.15 Catalina DMG file using the terminal. Now follow the below instructions to create a macOS 10.15 Catalina ISO File.

How to Create macOS Catalina ISO File?

Basically you can not create the macOS 10.15 Catalina ISO, as you did to the dmg file. So, to create an ISO file of the macOS 10.15 Catalina, you have to convert the macOS 10.15 DMG file to an ISO file. To do that follow the below procedures.

Following the above steps after creating the macOS 10.15 Catalina DMG file, type the below command in the Terminal.

hdiutil convert /tmp/Catalina.dmg -format UDTO -o ~/Desktop/Catalina.cdr

In the final step you have to rename and move the file to the desktop using the below command.

mv ~/Desktop/Catalina.cdr ~/Desktop/Catalina.iso

 

Step by step guide to create macOS Mojave ISO DMG File

These are the commands that the lamehacker inside the Github used it to create a macOS Mojave DMG and ISO file. Use all the commands one by one inside the terminal.

hdiutil create -o /tmp/Mojave.cdr -size 6g -layout SPUD -fs HFS+J
hdiutil attach /tmp/Mojave.cdr.dmg -noverify -mountpoint /Volumes/install_build
sudo /Applications/Install\ macOS\ Mojave.app/Contents/Resources/createinstallmedia --volume /Volumes/install_build
mv /tmp/Mojave.cdr.dmg ~/Desktop/InstallSystem.dmg
hdiutil detach /Volumes/Install\ macOS\ Mojave
hdiutil convert ~/Desktop/InstallSystem.dmg -format UDTO -o ~/Desktop/Mojave.iso
mv ~/Desktop/Mojave.iso.cdr ~/Desktop/Mojave.iso
rm ~/Desktop/InstallSystem.dmg

 

13 thoughts on “How to Create macOS Catalina ISO DMG file?”

    • To fix this problem, make sure that the macos is downloaded from the app store. To fix the problem incase the command didn’t work, type sudo, then go to the applications and drag the macOS Catalina app to the terminal. After that right click on the macOS Catalina App and open contents and resources directories, find their the create install media and drag that to Terminal. Once both of them are added, drag the USB location and at the end add the — nointeraction.

      Reply
    • Hi, I’ve tried following the instructions several times but keep getting the same error:

      Last login: Tue Aug 11 09:49:09 on console
      andrew@Andrews-MacBook-Pro ~ % hdiutil create -o /tmp/Catalina -size 8900m -volname Catalina -layout SPUD -fs HFS+J
      created: /tmp/Catalina.dmg
      andrew@Andrews-MacBook-Pro ~ % hdiutil attach /tmp/Catalina.dmg -noverify -mountpoint /Volumes/Catalina
      /dev/disk2 Apple_partition_scheme
      /dev/disk2s1 Apple_partition_map
      /dev/disk2s2 Apple_HFS /Volumes/Catalina
      andrew@Andrews-MacBook-Pro ~ % sudo /Applications/Install\ macOS\ Catalina.app/Contents/Resources/createinstallmedia –volume /Volumes/Catalina
      Password:
      Ready to start.
      To continue we need to erase the volume at /Volumes/Catalina.
      If you wish to continue type (Y) then press return: y
      Erasing disk: 0%… 10%…
      Error erasing disk error number (22, 0)
      An error occurred erasing the disk.
      andrew@Andrews-MacBook-Pro ~ %

      I’ve searched for hours but could not find a resolution. Does anyone have any ideas what is causing the error and how to fix it?

      Reply
  1. im getting error ‘hdiutil’ is not recognized as an internal or external command,
    operable program or batch file. and way to fix this?

    Reply

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