How to perform a clean install of macOS 10.15 Catalina

This article guides you through the process of performing a clean install of macOS 10.15 Catalina using a bootable USB method, instead of upgrading your Mac using Apple's standard installation package, retaining existing data and all applications. installed by the user.

Creating a bootable USB gives you a convenient way to install a new copy of macOS Catalina on multiple Macs. Doing a clean install can also eliminate annoying phenomena and strange behaviors that your Mac may experience over time, often helping to regain space due to junk files or third-party applications. three leave.

To follow the steps in this article, you'll need a blank 16GB or larger USB (USB-C or USB-A, depending on the Mac) and 1 or 2 hours of downtime to wait for the installation to complete. socks.

Also, make sure to back up the entire Mac first with Time Machine so you can restore the original system from the Recovery partition if something goes wrong.

Compatibility check

‌MacOS Catalina‌ is a major update that introduces a host of new features and changes, including cross-platform support for third-party apps, no longer iTunes, iPad as the second screen, Screen Time, etc .

Any Mac that can run macOS Mojave will run ‌macOS Catalina‌, except for Mac Pro models between 2010 and mid 2012. The full list of compatible Mac models is as follows:

1. MacBook (early 2015 or newer)
2. MacBook Air (Mid 2012 or newer)
3. MacBook Pro (Mid 2012 or newer)
4. Mac mini (Late 2012 or newer)
5. iMac (Late 2012 or newer)
6. iMac Pro (2017)
7. ProMac Pro‌ (Late 2013)

To check if your Mac is compatible, open the Apple menu in the upper left corner of the Mac screen and select About This Mac . Look directly below the OS X version number in the Overview tab - if the Mac model name is the same or newer than the options in the compatibility list above, then your Mac is compatible with ‌macOS Catalina‌.

How to perform a 'clean' installation of ‌macOS Catalina‌

1. Download ‌macOS Catalina‌ from Mac App Store.

2. When the download is complete, close the installer window by selecting the Quit Install macOS option in the menu bar or using the keyboard shortcut Command/⌘ + Q

3. Launch the Terminal application (found in Applications> Utilities> Terminal ).

4. At the Terminal command prompt , type sudo followed by a space.

5. Next, open the Finder window, navigate to the Applications folder, right-click (or press Ctrl ) on macOS 10.15 installer and select Show Package Contents from the context menu.

6. Navigate to Contents> Resources in the installer package.

7. Drag the createinstallmedia file into the Terminal window .

8. Still in the Terminal window, enter:

 /Applications/Install macOS Catalina.app/Contents/Resources/createinstallmedia --volume /Volumes/XXXXX 

But replace XXXXX with the name of the USB you plan to use as a bootable installer.

9. When you have replaced the XXXXX at the end with the name of the USB, press the Enter key on your keyboard to run the completed Terminal command.

10. Enter the admin password when prompted.

11. Type Y and press Enter when prompted and the command will create the Catalina installer that can boot on USB. This will take a few minutes to complete, so let it run until you see the "Install media now available" message . Note that if asked if you want to install Xcode in the process, you can click Not Now and the process will complete successfully.

Reboot and install

You can install Catalina on your Mac as soon as the USB installer is created. To do so, restart your Mac and hold the Option/⌥ phím key as soon as you hear the restart sound. Then follow these steps:

1. Use the mouse cursor or arrow keys on the keyboard to select the drive named Install ‌macOS Catalina‌ in the list that appears on the screen.

2. Once the USB has booted, select Disk Utility from the Utilities window, select the Mac boot drive from the list and click Erase.

3. When the Mac's boot drive is formatted, go back to the Utilities window and select Install macOS , select the newly erased boot drive when asked where to install the operating system, and follow the on-screen prompts to complete the installation. .

To install Catalina on another Mac, first make sure it is powered off, then simply plug in the USB installation tool you created and turn on the Mac. When you hear the start tone, press and hold the Option/⌥ phím key and follow the three steps above.