Solution for changing Big Sur login wallpaper to custom.

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Welcome, dpacheco_utd, to Apple Support Communities!

If your «startup screen» (user selection screen, login screen, or whatever Apple calls that screen) shows more than a single User choice (including any Guest users), then the “solution” presented in this Discussion will not help.

(Usually, the screen with the Apple logo, and the progress bar, seems to be called the “Startup screen”.)

If you can eliminate all users (including Guest users), other than your User Account, then you can follow the steps presented in this Discussion.

None of us have found a solution for multi-user systems, yet.

sallyrf wrote:

I followed all your very clear directions but it made no difference on my 2020 MacBook Pro. Do you have any other ideas? …

Do you have a Single User system: no other users, not even the Guest user?

If you have any other users, these directions won’t help much at all.

Did you disable FileVault? If FileVault is enabled, the result will be the same ol’ Login Screen (rather than the personal Lock Screen).

Is your Login set to show a list of your system’s Users, or to Username/Password? This was not included in the original set of instructions, because the List of Users is the usual default. Username/Password will always show the Login Screen (the «Big Sur Graphic.heic»).

The lock screen image (Big Sur Graphic.heic) is in the System/Library/Desktop Pictures folder and I can't make any changes to this folder no matter what I try.

Thanks. Sally

Yes. You are quite correct where the Login Screen (and default Lock Screen) is found.

However. That volume is a Read-Only volume, so, no, you cannot make any changes, there.

(If we could make changes, there, even those of us with multi-user systems would be able to change the Login Screen.)

It seems that the default startup wallpaper is in /System/Library/Desktop Pictures/Big Sur Graphic Day.heic with links to it. So theoretically one would have to change one of these links using the method described for Catalina. However this particular folder seems to be part of the sealed filesystem (the startup wallpaper is no doubt critical for the system). As I understand this protection, you have to renounce forever to the SSV protection since it seems not possible to sign the changes you made; indeed this is the point of this protection: not being able to make any change to system files. (see https://forums.macrumors.com/threads/words-of-caution-regarding-modification-of-system-files-using-csrutil-authenticated-root-disable.2276764/). So I guess the only safe way is to indicate our displeasure to Apple via https://www.apple.com/feedback/macos.html and hope somebody will listen.

Mbbrown55,

I assume you have a Desktop Pictures folder located in Macintosh HD > Library > Caches.

For step 10 within the Desktop Pictures folder, there is a folder with your UUID value as the name. Right click that folder and come down to Get Info. Next click the lock at the button of the get info window and enter your admin password to your Mac to grant permission. Where it says Sharing and permissions select Read & Write for your user account, admin and Everyone.

You might have to click the + button to add the admin if it's not showing in the list.

For FileVault and Guest user, go to System Preferences. Click Security and Privacy and then click the tab for FileVault and make sure it's off.

Next for guest user, go to Users & Groups and make sure Guest user is off.

To change the desktop picture go to desktop and screensaver and change the desktp picture to the one of the big sur landscape which should cause the lockscreen.png file to be automatically created.

Reboot your Mac and your login screen should match your desktop picture.

Hope this helps.

Welcome, E. Kennedy, to Apple Support Communities!

I see you have not had success with applewarm‘s suggestions.

Unfortunately, there are a few nuances that were not included in applewarm‘s original suggestions:

1. Such only work for truly Single-User systems: hence the reason for having to disable the Guest account. Multi-User systems will always see the Login Screen (always the colorful Big Sur Graphic image), prior to choosing a User (provided the system is not using the Username/Password dialogue for logins).
2. Those suggestions don’t take into account that some people have chosen to use the Username/Password dialogue for logins: this approach, even for a Single-User system, will never show the user’s Lock Screen (with the possible exception of the user explicitly putting their computer into Locked mode). One will always see the colorful Login Screen with the Username/Password dialogue for logins.

None of us have found a way to replace the background of the Login Screen: it’s always the colorful Big Sur Graphic image.

Does any of the above help you see why your system is not doing what you want?

I did create the folder and the folder with the userID. I did everything as described, but still have that ugly login screen. disabled firevault. this is a single user laptop. so what did I fail to do?

pantload wrote:

Does this work for a mac that has multiple users? Does it get rid of the bright Multi-color big sir graphic doing this?

I have a multi user machine and this doesn't work...

Sorry, pantload, but this process does not work on «multi user machine[s]».

On Single-User machines, this process helps the system recognize that the system is Single-User.

This, then causes the Login Window to be skipped: the system skips to the Lock Screen of the recognized Single-User. (That is, provided the Login Window is set to “List of users”, rather than “Name and password”.)

On Multi-User systems the system cannot skip the Login Window (the one with «the bright Multi-color big sir graphic»).

None of us have found a workaround to change the background image of the Login Window.

Welcome, Moka.s-Onkel, to Apple Support Communities!

The provided “solution” only works for Single-User systems. (The steps are, actually, to make a Single-User system be recognized as such.)

In the case of recognized Single-User systems (with the Login Screen set to “List of Users”, rather than “Username and Password”), the Login Screen is actually skipped, and starts at the Lock Screen of the single user.

The user’s Lock Screen is always (when everything works correctly) based upon that user’s Background image.

We have yet to find out how to change the background image of the actual Login Screen.

The best course of action, especially for Multi-User systems, is to provide Feedback, to Apple, concerning the desire to change the background of the actual Login Screen: Product Feedback - Apple.

One could, likewise, request means for setting a user’s Lock Screen to have a background that differs from the user’s working Background.

Welcome, ted2019, to Apple Support Communities!

Have you made sure that all the other conditions are met on your system?

The conditions are necessary to make sure that your system is recognized, by the macOS, as a Single-User system.

Multi-User systems are not helped by the provided settings.

However, there is one additional setting that was neglected: making sure the “Display login window as:” is set to “List of users”, and not “Name and password”.

What this all does is cause the Login Window to be skipped, skipping into the system’s Single-User’s Lock Screen (showing the lockscreen.png image for that user).

Only 1 user account and Guest user account is off, yes.

FileVault is off, yes

But your 3rd question made me get to the temporary solution: When I changed the 'Login Options' to 'Display login window as: List of users' (instead of 'Name and password' as I had it), it gave me my chosen 'Desktop Background' on the login screen after a restart and/or new start.

This is obviously just a workaround and I have amended my bug report to Apple, as you shouldn't need to compromise security (FileVault and/or login windows).

I took the approach of visiting the Users & Groups Preferences panel, and altering the Login Options to Display login window as: ⦿ List of Users. A logout or log-in now shows my chosen Desktop wallpaper with my avatar above my name and password window. Gone is the ghastly bright Apple genuine migraine wallpaper.

The avatar window does not support transparency, but it might get a dark background shortly.

As VikingOSX said, change to 'list of users' rather than trying to change the Big Sur boot up image.

My system has never had a different 'log in' and desktop. Whenever I've right clicked on an image and selected 'set desktop wallpaper', it's always changed both.

However, the boot up one has always been whatever Apple set it to when changing the OS.

If your log in options are changed to 'list of users' as stated, the boot up image will be whatever your wallpaper is.

My guest user is always turned off, so if you have this on, you might need to turn it off—I'm not sure.

This method 100% works. Just have to make sure FileVault is off and the permissions have been set as detailed. When you go back to look in the folder it will take macOS a moment to generate the file but it creates itself rest assured.

Welcome, bmwapple, to Apple Support Communities!

If you have followed all the instructions, provided by applewarm, «to the letter», as you say, does that mean that you have only a single user on your system, including no Guest user?

Unfortunately, there was one thing that applewarm missed: making sure the “Display login window as:” is set to “List of users”, and not “Name and password”.

What this all does—on systems that are recognized, by macOS, as Single-User systems—is cause the Login Window to be skipped, skipping into the system’s Single-User’s Lock Screen (showing the lockscreen.png image for that user).

Unfortunately, none of this helps Multi-User systems, since they will always display the Login Window, that always shows the Big Sur Graphic image (the brightly colored, artists impression of Big Sur [perhaps at sunset]).