Mac Clean Install

The steps below are for Catalina but it should be the same for other versions of macOS.

  1. Ensure you have a Time Machine backup and have iCloud configured to backup important app settings, e.g. Documents, Device Settings, Mail, Contacts, Keychain, etc. and everything is synchronised to the iCloud server.
  2. Make a list of installed Applications for later use as follows:
    • In Finder open Applications folder and press Command+A to select all apps, then press Command+C
    • In TextEdit, create a new document, select Format -> Make Plain Text from the menu bar, press Command+V to paste list of app names into the document and print it out or save it to the desktop and copy it to the Time Machine drive.
  3. Create a bootable MacOS usb installer, e.g. Catalina – see Apple Support instructions *
  4. Insert your “Install macOS Catalina.app” bootable usb.
  5. Power up.
  6. Hold the OPTION key until the boot selection menu appears.
  7. From macOS Utilities window choose Disk Utility
  8. Select the Mac HD drive and select Erase
  9. Set format as APFS and click Erase
  10. Quit to main menu
  11. Select Install MacOS and follow instructions. When it comes to Migration Assistant connect your Time Machine or Time Capsule (for which you’ll need your login password) drive. Then
    1. Untick Applications (to avoid reinstalling 3rd party programs)
    2. Tick Users
    3. Tick “Other Files and folders”
    4. Tick “Computer & Network Settings”
  12. Click Continue to restore your data and settings.
  13. Follow the installation wizard to complete installation
  14. If necessary clean up Safari by using the following instructions  Safari Manual Reset
  15. Install required 3rd party programs – refer to list (apps.txt) produced in step 2.

This completes the Clean Install.

  • Note when downloading MacOS from the App Store completes it automatically enters the “Install macOS Catalina” app. If not shown on the desktop it can be seen by clicking on the “Install macOS Catalina” app minimised on the right-hand-side of the Launchpad. Once here type Command+Q to quit the application. The “Install macOS Catalina.app” should be in the Applications directory ready to be copied to usb. For Catalina your usb needs to be larger than 8GB, e.g. 16GB

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