Create a Bootable USB Stick from an Older Version of macOS

Download the version of the OS you want to install here: https://support.apple.com/en-gb/HT211683

Open InstallMacOSX.dmg by double-clicking.

Double-click on InstallMacOSX.pkg

The installer runs

If you don't get the following error: "This version of OS X/macOS cannot be installed on this computer."

Wait for the end of the installation and follow the following tutorial : Creare una chiavetta USB avviabile

Otherwise, go to the next step.

Quit the installer and drag and drop the InstallMacOSX.pkg file on your Desktop

Open Terminal and enter the following command: "cd Desktop"

Enter the following command: "pkgutil --expand ~/Desktop/InstallMacOSX.pkg FolderName" (You can change FolderName to any name you want)

A folder with the name you gave appears on your Desktop.

Open the folder appeared on the desktop.

Then, download the files here: https://github.com/ThonyF/iFixitTutoCrea...

Search for the macOS version corresponding to the installation you wish to perform and replace the distribution file in the folder that has been created.

Go back to the terminal and type the following command: pkgutil --flatten FolderName New.pkg (FolderName = the name of the folder and New.pkg = the new .PKG file that will be created)

Press enter and wait for the file to be created

Launch the new .PKG file

Congratulations you can launch the installer.

To continue creating the USB Stick follow the following tutorial : Creare una chiavetta USB avviabile