Q: Can not load user & groups Preference Pane

a way to remedy the situation

What way was that? Was this an Apple Support representative?

Is the problem that you can't open System Preferences at all, or that you can't open the Users & Groups preference pane? Can you do it in your other accounts?

Please read this whole message before doing anything.

This procedure is a test, not a solution. Don’t be disappointed when you find that nothing has changed after you complete it.

Step 1

The purpose of this step is to determine whether the problem is localized to your user account.

Test while logged in another user. Same problem?

Step 2

The purpose of this step is to determine whether the problem is caused by third-party system modifications that load automatically at startup or login, by a peripheral device, by a font conflict, or by corruption of the file system or of certain system caches.

Please take this step regardless of the results of Step 1.

Disconnect all wired peripherals except those needed for the test, and remove all aftermarket expansion cards, if applicable. Start up in safe mode and log in to the account with the problem.

Note: If FileVault is enabled in OS X 10.9 or earlier, or if a firmware password is set, or if the startup volume is a software RAID, you can’t do this. Ask for further instructions.

Safe mode is much slower to start up and run than normal, with limited graphics performance, and some things won’t work at all, including sound output and Wi-Fi on certain models. The next normal startup may also be somewhat slow.

The login screen appears even if you usually log in automatically. You must know your login password in order to log in. If you’ve forgotten the password, you will need to reset it before you begin.

Test while in safe mode. Same problem?

After testing, restart as usual (not in safe mode) and verify that you still have the problem. Post the results of Steps 1 and 2.

What exactly happens when you try to boot in safe mode, following the instructions linked to my earlier comment? If you use a wired keyboard, it should be connected to a built-in USB port, not a hub.

A

Please take these steps to restore administrator privileges to your account. This somewhat tedious procedure is only necessary if you've confirmed that no working administrator account exists on the system.

If you don't already have a current backup of all your data, you must back up before taking any of the steps below. Ask if you need guidance. You won't need the backup unless something goes wrong—which is always possible.

Step 1

Start up in Recovery mode. The OS X Utilities screen will appear.

Step 2

Take this step only if you use FileVault 2. Launch Disk Utility, then select the icon of the FileVault startup volume ("Macintosh HD," unless you gave it a different name.) It will be nested below another drive icon. Select Unlock from the File menu and enter your login password when prompted. Then quit Disk Utility to be returned to the main screen.

Step 3

Select

          Utilities ▹ Terminal

from the menu bar. In the window that opens, type this:

resetp

Press the tab key. The partial command you typed will automatically be completed to this:

resetpassword

Press return. A Reset Password window opens. Select your startup volume if not already selected. Pull down the menu labeled

          Select the user account

and select

          System Administrator (root)

Follow the prompts to set a password. It's safest to choose a password that includes only the characters a-z, A-Z, and 0-9. I suggest you write down the password. If you don't write it down and forget it, you'll have to start over from Step 1.

Select

           ▹ Restart...

from the menu bar.

Step 4

This step, like Step 2, applies only if you use FileVault. Log in as usual, then select

           ▹ Log Out...

from the menu bar, or press the key combination shift-command-Q. Don't restart. You'll be returned to the login screen.

Step 5

At the login screen, click Other... Enter "root" (without the quotes) in the Name field, and enter the password you set in Step 3 in the Password field. You should now be logged in as root. This is a potentially dangerous condition. Do nothing while logged in as root except as indicated below. You'll be fine as long as you don't deviate from the plan.

Open the Users & Groups preference pane. Select your usual administrator account in the list of users and check the box marked

          Allow user to administer this computer

You'll be prompted to restart. Do that and log in as yourself—not as root. Your administrator status should now be restored.

Step 6 (optional, but recommended)

Follow the instructions in this support article under the heading "How to disable the root user." You must authenticate in Directory Utility as "root" with the root password you set in Step 3. Authenticating as another administrator won't work.

Credit for this idea to ASC member wessongroup.

B

Please back up all data before proceeding.

This procedure will unlock all your user files (not system files) and reset their ownership, permissions, and access controls to the default. If you've intentionally set special values for those attributes on any of your files, they will be reverted. In that case, either stop here, or be prepared to recreate the settings if necessary. Do so only after verifying that those settings didn't cause the problem. If none of this is meaningful to you, you don't need to worry about it, but you do need to follow the instructions below.

Step 1

If you have more than one user, and the one in question is not an administrator, then go to Step 2.

Triple-click anywhere in the following line on this page to select it:

sudo find ~ $TMPDIR.. -exec chflags -h nosappnd,noschg,nosunlnk,nouappnd,nouchg {} + -exec chown -h $UID {} + -exec chmod +rw {} + -exec chmod -h -N {} + -type d -exec chmod -h +x {} + 2>&-

Copy the selected text to the Clipboard by pressing the key combination command-C.

Launch the built-in Terminal application in any one of the following ways:

☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)

☞ In the Finder, select Go ▹ Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.

☞ Open LaunchPad and start typing the name.

Paste into the Terminal window by pressing command-V. I've tested these instructions only with the Safari web browser. If you use another browser, you may have to press the return key after pasting.

You'll be prompted for your login password, which won't be displayed when you type it. Type carefully and then press return. You may get a one-time warning to be careful. If you don’t have a login password, you’ll need to set one before you can run the command. If you see a message that your username "is not in the sudoers file," then you're not logged in as an administrator.

The command may take several minutes to run, depending on how many files you have. Wait for a new line ending in a dollar sign ($) to appear, then quit Terminal.

Step 2 (optional)

Take this step only if you have trouble with Step 1, if you prefer not to take it, or if it doesn't solve the problem.

Start up in Recovery mode. You may be prompted to select a language, then the OS X Utilities screen will appear.

If you use FileVault 2, select Disk Utility, then select the icon of the FileVault startup volume ("Macintosh HD," unless you gave it a different name.) It will be nested below another drive icon. Select Unlock from the File menu and enter your login password when prompted. Then quit Disk Utility to be returned to the main screen.

Select

          Utilities ▹ Terminal

from the menu bar. A Terminal window will open. In that window, type this:

resetp

Press the tab key. The partial command you typed will automatically be completed to this:

resetpassword

Press return. A Reset Password window will open. You’re not going to reset a password.

Select your startup volume ("Macintosh HD," unless you gave it a different name) if not already selected.

Select your username from the menu labeled Select the user account if not already selected.

Under Reset Home Directory Permissions and ACLs, click the Reset button.

Select

           ▹ Restart

from the menu bar.