If you use pkgutil to expand the InstallMacOSX.pkg it opens to three items, the Distribution file, InstallMacOSX.pkg and Resources. You can alter the Distribution file to ignore the supported platform check, see below.
METHOD 1: Using DiskMaker X. Run, DiskMaker X, then.choose El Capitan (10.11). Double click on El Capitan.DMG to mount it, then borrow the El Capitan.app. Select the USB volume name, then select Choose this disk. Click on Erease to format the USB and create the disk. Click Continue, you then are asked for admin and password. Download and keep a copy of the ‘Install OS X El Capitan’ App. (Download from App store but make a copy of it before you install it as the Apple Installer deletes it after you use it.) Put it in your ‘Applications’ folder. Format your blank USB (8GB is a good size) as Apple OS X Extended (Journaled) using Disk Utility and call it.
Creating the Install OS X El Capitan.app on a mac that came with a newer OS than El Capitan.
Download the InstallMacOSX.dmg from Section 4 of How To Upgrade To El Capitan
Double-click to open InstallMacOSX.dmg to Install MacOSX.pkg.
Drag InstallMacOSX.pkg to the Desktop.
Open Terminal, enter the text
A folder will be created on the Desktop after a while with the contents of the .pkg file.
In there you will see an item called Distribution, Control-click on that and select Open With
go to Other and select Text Edit.
When the file opens scroll down to the section that reads,
function isSupportedPlatform(){
type in at the end return true; so it now reads as,
function isSupportedPlatform(){return true;
Now click Save and close the document.
Go back to Terminal and enter the text,
press Return, after several minutes, be patient, (check to see if the prompt has returned to Terminal) a new package will be created on the Desktop.
When created double-click on that and an installation window will open where you will now convert the
new InstallElCapitan.pkg to the Install OS X El Capitan.app which will be placed in your Applications folder.
You can now create a bootable USB using the install app and createinstallmedia,
Create Bootable Usb Os X
If you have the time I would be grateful if you could give this a trial, it works here on my mac, but I would like confirmation from yourself or any others reading this that the procedure works on macs that came with macOS Sierra or newer pre-installed. Oh and tell me if my description of the procedure is easy to follow and understand..
Os X El Capitan 10.12
Jan 15, 2020 12:58 AM