Back up all your data using Time Machine or an external clone, as this process will erase everything on your Mac. Phase 2: Download macOS Catalina
Performing a clean install of macOS Catalina (10.15) is the most effective way to eliminate system bloat, resolve persistent software bugs, and start fresh with a responsive operating system. Unlike a standard upgrade, a clean install wipes your primary drive entirely before installing the OS. mac os catalina download clean install
A USB flash drive with at least 16GB of storage is required to create the bootable installer. Back up all your data using Time Machine
Before you begin, ensure your Mac and equipment meet the necessary requirements: A USB flash drive with at least 16GB
Confirm the download. When the installer automatically opens after finishing, . The file must remain in your /Applications folder. Phase 3: Create a Bootable USB Installer