Create Catalina Installer

Create Catalina Installer

Build a bootable USB installer for macOS Catalina using the official installer app and command-line tools. This process creates a clean, unmodified installer that works with OpenCore.

Prerequisites

  • A USB drive with at least 16GB capacity (USB 3.0 recommended)
  • macOS High Sierra (10.13.6) or later as the host system
  • macOS Catalina installer downloaded from the Mac App Store
  • ProperTree and your EFI folder ready

Download Catalina

  1. Open the Mac App Store on your host Mac.
  2. Search for "macOS Catalina" and download it.
  3. The installer will appear in your Applications folder as "Install macOS Catalina.app".

Note: If you don't have access to the Mac App Store, you can use gibMacOS or other tools to obtain the installer.

Format the USB Drive

Use Disk Utility to prepare your USB drive:

  1. Insert your USB drive.
  2. Open Disk Utility (Applications → Utilities → Disk Utility).
  3. Select your USB drive in the sidebar.
  4. Click "Erase" at the top.
  5. Name: "Catalina" (or your preference)
  6. Format: Mac OS Extended (Journaled)
  7. Scheme: GUID Partition Map
  8. Click "Erase" and confirm.

Create the Installer

Open Terminal and run the following command:

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

This will take several minutes. The USB drive will be renamed to "Install macOS Catalina".

Add OpenCore EFI

  1. Mount the EFI partition of your USB drive (use Disk Utility or mount_efi.sh script).
  2. Copy your prepared EFI folder to the mounted EFI partition.
  3. Ensure the EFI folder contains your config.plist, drivers, kexts, and ACPI files.

Verify the Installer

Restart your Mac and hold Option during boot to see the boot menu. You should see "Install macOS Catalina" as a boot option.