The computer will restart automatically during installation. Leave the USB drive plugged in until the system opens the initial Mac Setup Assistant welcome screen.
If you have an older Mac or the App Store refuses to cooperate, Apple Support provides DMG files directly on their website.
: Minimum 20 GB of free storage space available on your boot drive. Memory : At least 4 GB of RAM (8 GB recommended).
If the "Get" button is greyed out, your Mac may not meet the system requirements or the installer may be unavailable through the App Store. In that case, try one of the other methods. The computer will restart automatically during installation
I can provide specific troubleshooting steps or alternate terminal scripts based on your hardware. Share public link
Press again. Terminal will ask for verification to erase the destination drive. Type Y and press Enter .
If the command line feels intimidating, use a tool like or Mac Install Disk Creator . These apps provide a graphical interface: select your USB drive, choose the macOS installer, and click a button. The tool handles the rest. : Minimum 20 GB of free storage space
On Intel Macs, the Option key must be pressed as soon as you hear the startup chime. On Apple Silicon, ensure you are pressing and holding the power button long enough—until the startup options actually appear.
Method 3: Direct DMG Download Links (For Windows/Linux Users)
, the most reliable way to get the installation file is directly from Apple. Using official sources ensures the installer is secure, complete, and compatible with your hardware. 1. Download the macOS Catalina Installer In that case, try one of the other methods
If the App Store method fails, there are reputable sources that still host macOS Catalina DMG files. after downloading (see Step 3).
shasum -a 256 "/Applications/Install macOS Catalina.app/Contents/SharedSupport/InstallInfo.plist"
Before proceeding, confirm that your hardware supports macOS Catalina 10.15. Hardware Prerequisites
After downloading, you must verify the file’s authenticity. Apple publishes SHA‑256 hashes for its installers; your file’s hash should match.
Avoid shady “macOS download” websites. Apple may not sell Catalina anymore, but the DMG files are still legally obtainable via open-source tools and Apple’s own CDN.