Solution for changing Big Sur login wallpaper to custom.

You said at the end “Enjoy”

I did, and I do 😁

Thanks for this 👍🏻

Which Library is this? Your user Library > Caches or Macintosh HD > Library > Caches?

I assume it's Macintosh HD > Library > Caches.

That's a screenshot of Macintosh HD or in my case MacOS Big Sur > Library > Caches. it looks like I don't have the Desktop pictures folder. I wonder why one might have it and other don't?

Thanks, please clarify.

applewarm wrote:

Ok so by default just follow the original instructions to the letter.

First steps in my original post. Then:

Copy your UUID value.

Go to Library > Caches > Desktop Pictures.

Inside Desktop Pictures create a new folder and name it with your UUID.

Grant permissions to Read&Write for this new folder.

That's it. Nothing more.

The lockscreen.png file (it's the file for the login screen wallpaper - the one you see when restarting/turning on - aka the ugly colourful Big Sur we're customising) inside the UUID-named folder will automatically be re-created/modified by your computer every time you change your desktop wallpaper, so that the login background and the desktop wallpaper will match.

Now in your case in particular it looks like you already have the UUID folder and don't need to create anything, and you already have a lockscreen.png file inside the UUID folder. You should be already set... So do your login wallpaper and desktop wallpaper match already? Then that's great and you don't need to do this procedure at all.

If they don't match and you have the ugly colourful Big Sur login wallpaper still, then try leaving everything as it already is and just delete your current lockscreen.png file, and also make sure the permissions for your UUID folder are on Read&Write. Now if you change your desktop wallpaper and restart your computer you should be rid of the ugly colourful Big Sur login.

Thanks, however...

Filevault is off just for the record. A guest account is enabled just for the record.

Tried as you discribe above— the mystery is it does not work, and restart/reboot or shutdown/reboot I still get the colorful BS background until I hit my user to log in. This is the way it was before as well.

Just trying to corroborate your methodology here....maybe having the guest account option throws this off(?)

With a bit more testing —YES — it is the guest account that throws it off.

note: without Filevault... I always want the guest account enabled— in this way if stolen it allows the computer to get on line...

applewarm wrote:

1. Just sharing a solution I've found on Stack Exchange. Credit to whoever discovered it.

System Preferences > Users & Groups.

2. Open lock to make changes.

3. Right click on user in left column > Advanced Options.

4. Copy UUID value.

5. Go to /Library/Caches/Desktop Pictures.

6. If it doesn't exist create Desktop Pictures folder.

7. Inside Desktop Pictures create folder with UUID value as name.

8. Right click on folder > Get Info.

9. Open lock to make changes.

10. Grant permission to Read & Write to user, admin, everyone.

11. Make sure FileVault and Guest user are deactivated.

12. Change desktop wallpaper.

13. Restart computer.

Big Sur will now always create a lockscreen.png file in the UUID folder matching the current wallpaper.

Tested on a 2018 MBP and works perfectly.

Enjoy!

Your #11. Make sure FileVault and Guest user are deactivated.

Should be moved to #1 if you keep posting this across the board.

Good explanation, followed it step by step, but ultimately sorry, no, it did not work for me (mac mini 2018). What was Apple thinking when they created that login screen; I have hardly ever seen anything like it. Please Apple, please.

I already checked the lockscreen.png in my UUID folder, applewarm: it already matches my recently changed desktop wallpaper.

The very fact that the folders are given the UUIDs of specific users, already suggest that they should not be used for the login screen.

When there is only a single user on the system (only a single user UUID and no Guest account), then, and only then, does it make sense for the login screen to match the desktop wallpaper of said single user.

Otherwise, it makes no sense for the login screen to match the desktop wallpaper of any single user. (Incidentally, I have two administrative users, on my system.)

Not sure if this is where you're stuck, but it's what finally fixed it for me: in System Preferences > Security & Privacy > FileVault, it's turned on by default and you'll see the "Turn Off FileVault..." button grayed out so you'll have to click on the lock icon in the lower left corner and enter your password to change the setting. The button will then be enabled; follow the prompts to turn off encryption and you're done.

I hope this helps!

it does not work for me - as ocifeRed wrote, this might change the login-screen _after_ picking one of the users (that worked for me before) - but I would like to get rid of the very bright and colorful background after booting the machine and when the first screen appears where you can choose which user to log-on.

Could it be that you are having a single-user config?

Applewarm, thank you SO much! Worked right away! A Miracle, wow! :) So happy!

I'd like to bring to the attention of some inexperienced users though, as I had this puzzle as well:

You may easily confuse 2 different folders: system/library/desktop pictures WITH this one:

/library/caches/desktop pictures

You can't make any changes in the first one. - I had to create a new folder in /library/caches and followed all the steps described in the instructions above and it worked! Login/start desktop changed to the same image as my desktop screen after these manipulations and restart! Can't express how happy I am to find this solution as the pic was really ugly and disturbing.

Many thanks everyone. I have tried all kind suggestions in all possible sequences but regrettably none worked for me. So therefore now @Apple: can you pls kindly help and create an update so as to assist ignorant people like myself to properly remove or replace that newly created and 'somewhat-less-than-appealing' 'big sur' login-screen? Thank you!