Admin Password won't unlock Users & Groups so I can Add a New User

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The Mac Mini from 2018 does contain the Apple T2 Security Chip

Should the Original User Account, which is normally the Admin Account, has lost Admin Account Privileges

This could be the answer your issue " Admin Password won't unlock Users & Groups "

To test if this is so

if in doubt about admin from your logged in user account,  from Terminal.app copy and paste —

dscacheutil -q group -a name admin

Credit for above Terminal command to @leroydouglas

Depending on the Outcome of the Terminal Command.

Worst Case Scenario and Admin Privileges are in fact lost

Refer to this link from a well respected Contributor @Barney-15E

Restarting Setup Assistant to create Admi… - Apple Community

The implications from the previous link maybe bad news

" Note for Sonoma users

According to Apple, this method does not work on Sonoma. You have to Erase all Content and Settings. "

The link suppled is an edited version to include the link

l008com wrote:

Working on a customers computer today, trying to chase down a totally different, unrelated problem.

Which is?

So I figure, let me make a new user and see if the problem persists on the new account.

Makes sense.

No matter what, the password was good everywhere else, but it would not let me create a new user.

That's why it would be useful to know the original problem. It's probably the same problem. So it's pointless to worry about the symptom. Just fix the problem.

This is on the latest version of Sonoma, 14.5.

That is the latest version of Sonoma, but it was only released today. I'm guessing that whatever the problem is, lies with whatever the non-standard configuration this computer has.

p.XXXXXX@Ps-Mac-Mini-M2 ~ % dscacheutil -q group -a name admin

name: admin

password: *

gid: 80

users: root p. XXXXXX

If the final line reveals >> root << followed by the User Account Name

Then, they have Full Admin Privileges

Certain information has been altered ( XXXXX ) so as to not reveal my True Identity

If I may backup this up a bit

As Sonoma 14.5 was just released Monday May 13, 2024 at about 13:00 Hrs PDT Time

The computer was have to been updated .

To update from a previous version of Sonoma to current 14.5

That in and of itself would have Required a Full and Functioning Admin Account

So, any loss of Admin Privileges between than and now, would have occurred during the update process

A way to see the purpose and all the options for any Terminal commands use the man option.

Example:

man dscacheutil

(If the list ends with ":", just press spacebar to continue)

Press "Q" to exit the displayed man page.

l008com wrote:

The user list in system prefs shows the status of each user, and this user is an admin. Unless that window is somehow lying but that seems unlikely.

People have managed to lose admin capability on their only user, but I haven’t heard of that status indicator lying. Can you sudo in Terminal?

If I may ask

You keep making reference to System Preferences throughout this question

System Preferences WAS used in macOS 12 Monterey and older versions of macOS

It did get changed to System Setting in macOS 13 Ventura and above

Exactly what version of macOS is this Client actually using that has this issue ?

I didn't get a chance to check. I was in system prefs trying to lock and then unlock some panes but apparently that's not a thing anymore.

I doubt that would do any good. That was to enable only admin users to be able change certain things. You must be an admin user to create a new user.

The two things that might be involved is a Profile (possibly through Screen Time), and perhaps a malformed sudoers file (that's why I asked if you could do so in Terminal).

Refer to this link from a well respected Contributor @Barney-15E

Restarting Setup Assistant to create Admi… - Apple Community

That no longer works in Sonoma.

Plus theres only one user and that user is the admin.

Did you confirm that or just assuming since it is the only user it must have admin capability?