Changing the Mac login screen background requires manual system file changes since Apple doesn’t provide a built-in option. 2. You must have admin access, disable SIP via Recovery Mode, and back up your Mac before proceeding. 3. Prepare a high-resolution JPEG or PNG image and save it as login-background.jpg or .png. 4. Disable SIP by rebooting into Recovery Mode and using the Terminal command csrutil disable. 5. Navigate to /Library/Caches/, locate the com.apple.desktop.admin.png (or similar) file, and back it up. 6. Copy your custom image into the folder and rename it to exactly match the original filename. 7. Optionally, set proper permissions so System has Read & Write and Everyone has Read-only. 8. Re-enable SIP via Recovery Mode using csrutil enable for security. 9. Log out or restart to test the new login screen background. 10. After macOS updates, you may need to repeat the process as the background can reset. 11. For a safer alternative, use a matching desktop wallpaper, as the login screen often mirrors the admin user’s wallpaper. Always proceed with caution, back up your data, and ensure SIP is re-enabled after changes to maintain system security.

Changing the login screen background on a Mac isn't as straightforward as changing your desktop wallpaper—Apple doesn’t provide a built-in option for this, and the login screen image is system-protected. However, it is possible with some manual steps. Here’s how to do it safely and effectively.

?? Important Notes Before You Begin

• You’ll need admin access to make these changes.
• System Integrity Protection (SIP) must be temporarily disabled.
• This process involves modifying system files. Always back up your Mac (via Time Machine or another method) before proceeding.
• After macOS updates, your custom login screen may reset. You might need to repeat the process.

? Step 1: Prepare Your Custom Image

Choose a high-resolution image you'd like to use for the login screen.

• Recommended size: Match your display resolution (e.g., 1440x900, 2560x1600, etc.).
• Format: JPEG or PNG.
• Save it as login-background.jpg (or .png) on your desktop or another easy-to-find location.

? Tip: Avoid images with too much brightness or white—it can make login text hard to read.

? Step 2: Disable System Integrity Protection (SIP)

1. Restart your Mac.
2. Immediately hold Command (?) R to boot into Recovery Mode.
3. From the top menu, go to Utilities → Terminal.
4. Type the following command and press Enter:

   csrutil disable

5. Close Terminal and restart your Mac normally.

? Step 3: Replace the Login Background File

The default login background is stored in a system folder. You’ll replace it with your image.

1. Open Finder, press Command Shift G, and enter:

   

   /Library/Caches/

2. Look for a file named:

   com.apple.desktop.admin.png

   (Sometimes it's a .jpg or named differently—look for a large image file that matches your screen resolution.)

   If it doesn’t exist, macOS generates it from your current desktop wallpaper. To trigger this:

   • Change your desktop wallpaper to something new.
   • Log out and back in.
   • Check /Library/Caches/ again.

3. Once you find the file:

   • Rename the original (e.g., com.apple.desktop.admin.png.bak) as a backup.
   • Copy your custom image into this folder.
   • Rename your image to exactly match the original filename (e.g., com.apple.desktop.admin.png).

? You’ll need to authenticate with your admin password when copying.

? Step 4: Set Correct Permissions (Optional but Recommended)

To prevent issues, ensure the file has the right permissions:

1. Right-click the file in /Library/Caches/ → Get Info.
2. Under "Sharing & Permissions", make sure:
   • System has Read & Write.
   • Everyone has Read-only.
3. If not, click the lock icon, authenticate, and adjust.

? Step 5: Re-enable SIP for Security

Don’t leave SIP disabled—it’s a critical security feature.

1. Restart and boot into Recovery Mode again (hold ? R).
2. Open Terminal and run:

   csrutil enable

3. Restart.

? Step 6: Test the New Login Screen

Log out (or restart), and you should see your custom background on the login screen.

? If it doesn’t appear:

• Double-check the filename and location.
• Try logging in, changing your desktop wallpaper, then logging out again.
• macOS sometimes regenerates the cache file.

? After macOS Updates

System updates often overwrite or reset the login background. You may need to:

• Re-copy your image to /Library/Caches/.
• Re-apply permissions.
• (Sometimes) disable SIP again temporarily.

? Alternative (Safer but Limited): Use a Matching Desktop Wallpaper

If the above feels too technical or risky, simply set your desktop wallpaper to the image you want. The login screen often mirrors the admin user’s desktop background—especially if you're the only user.

To improve consistency:

• Use a clean, dark, or neutral image.
• Avoid clutter so login text stays readable.

Basically, yes—you can change the login screen background, but it involves system-level changes. Proceed carefully, back up first, and re-enable SIP when done. Not complex, but easy to mess up if rushed.

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