Changing the login screen background picture in macOS 10.15 Catalina is more difficult than in previous versions of macOS. The final process of replacing a .heic image in the Desktop Photos folder remains the same. Prior to completing this task, however, users must first disable System Integrity Protection (SIP) from within recovery mode.
Steps to change the macOS Catalina login screen image:
- Reboot system in recovery mode by holding command + r on startup.
- Open Terminal in recovery mode and enter the command “csrutil disable”.
- Reboot the system and login as an administrator.
- Open Terminal and enter the command (see note below) “sudo mount -t apfs -wu /dev/disk1s5/Volumes”.
- Enter the following command: “sudo mount -wu /; killall Finder”.
- Navigate to Computer -> Macintosh HD -> System -> Library -> Desktop Pictures.
- Rename the Catalina.heic file to Catalinaold.heic or a different unique file name.
- Move the desired login screen image into the Desktop Pictures folder.
- Rename the new file to Catalina.heic and then log out of the account to confirm changes.
Step 4 details: Replace the “disk1s5” part of the command with proper partition name for your computer.
Steps to find the correct disk partition name on macOS 10.15:
- Access the Apple Menu.
- Click on About This Mac.
- From the Overview tab, click on System Report.
- In the Hardware section, click on Storage.
- The correct disk partition name is listed next to BSD Name.
Steps to reenable System Integrity Protection on macOS 10.15:
- Restart the computer (this alone works on most systems).
- Hold down command+r to enter recovery mode.
- Open terminal.
- Enter the the following command: “csrutil enable”.
- Confirm the changes by entering “csrutil status”.
- Restart computer normally.
Terminal commands required to change the login screen background image:
sudo mount -t apfs -wu /dev/disk1s5/Volumes
sudo mount -wu /; killall Finder
Optional Terminal Commands: