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51 thoughts on “macOS Catalina: How To Change The Login Screen Background”

  1. You can find below the easiest way to change your lock-screen picture on MacOs Catalina:

    1. System Preferences > Security&Privacy > make sure FileVault is off.
    2. System Preferences > User&Groups > Right Click on User after you unlocked settings > Advanced Options > Copy UUID
    3. Go > Library/Caches > Make New Folder and rename to Desktop Pictures > Right click on the folder > Get info > Below where Sharing&Permissions is > make the admin read&write.
    4. Open the new folder named Desktop Pictures > Make another folder and name paste the UUID as the folder’s name > Get info on the new folder > make admin read&write as well.
    5. Reboot mac.
    6. Acces Library/Caches/ Desktop Pictures/ UUID folder > change picture with anything you want.
    7. Reboot computer.

    Reply
    • Did not work for me. I put the picture I wanted (a JPEG) into the UUID-named folder, rebooted, and got the same supervillain-volcano image on my login screen. Added the Administrator with read&write to the permissions on the JPEG, rebooted again, same result. Converted the JPEG to HEIC, added Administrator with read&write, rebooted. Login picture still unchanged.

      Does the file in the UUID-named folder need to have a special name? I feel like the instructions got really vague at step 6…

      Reply
  2. This worked a treat under Catalina, but not Big Sur. All okay up to Step 5:

    sudo mount -wu /; killall Finder

    where I get the response

    mount_apfs: volume could not be mounted: Permission denied
    mount: / failed with 66

    Really appreciate it if anyone can help. I hate the Log in BG…

    Cheers from London, Brett

    Reply
  3. I’ve found a solution which I have written in here.

    which I have written in here: https://apple.stackexchange.com/a/400036/333137

    i think in most cases it is the missing of a folder in “/Library/Caches/Desktop Pictures”

    this must be created with the name of the user’s UUID. In addition, the rights for the system to write must be set.

    after that macOS should put a “lockscreen.png” file for the login there again.

    Should work for Catalina and Mojave.

    Reply
  4. Great it works thanks, but please how to reverse this ?? I’m still getting System mounted on each start. any solutions ?

    Reply

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