On the left-hand pane, select the USB drive (not the partition under it, if any).Plug the USB flash drive into your Mac.If the USB flash drive is not already formatted as “Mac OS Extended (Journaled)”, format it like so: You don’t need to delete the existing content on the drive because we will blow it all away in a subsequent step. For example, you can move the “Install macOS Catalina” application to the “~/Downloads” directory and run it from there.īecause macOS Catalina is 8.4GB in size, you will need a 16GB USB flash drive. Note: If you plan to run the installer first to update your current macOS version to Catalina, you will want to move the “Install macOS Catalina” application out of the “/Applications” directory otherwise, the installer will delete itself from the “/Applications” directory when the upgrade completes.
If the installer automatically launches, just close it. It will be saved to the “/Applications/Install macOS Catalina” location. Go to the Mac App Store, search for “macOS Catalina”, and download it. (The Mac mini came with macOS 10.14 Mojave so I used it to download Catalina.) You will need a Mac to download macOS Catalina you can download Catalina from The Mac Go.
Note: The instructions below are the same for macOS 10.13 High Sierra and macOS 10.14 Mojave.
I purchased a used 2018 Mac mini desktop and wanted to put a fresh installation of the latest macOS 10.15 Catalina on it.
