Unable to install macOS Sequoia 15.6 on MacBook Pro

This portion of your original question is intriguing " This was a new password which I had been using for the past month following a recent change at the Apple Genius Bar. ?

What was it , that the Apple Genius Bar did, to cause you to create a new computer password ??

If you have forgotten the new password, then follow the link provided by my colleague

But first we need to establish if the existing new password is in fact

1 - the correct password

2 - if yes, does the current account have both Ownership and Admin Privileges

Below links will provide additional insights regarding the Difference between Admin Accounts and Owner Accounts  

https://eclecticlight.co/2021/07/18/last-week-on-my-mac-the-perils-of-m1-ownership/

https://eclecticlight.co/2024/07/29/ownership-means-two-different-things-in-macs-how-to-tell-them-apart/

Owl-53 wrote:

Below links will provide additional insights regarding the Difference between Admin Accounts and Owner Accounts  

Egad, that's a potential quagmire. Coincidentally, I just migrated my oldest child's 2019 MBAir to a new M4 MBP. I had set up the Air myself with me as the admin, but given that she's 17 now and probably will take the M4 MBP to college with her, I wanted her to be the admin. I got to the step of transferring users in Migration Assistant and almost transferred just her user instance and not mine. I suspect/hope that MA would have just made her the owner of the new Mac, though I didn't know about this distinction at the time. But to be safe, I terminated the migration, went back to the MBAir and made her an admin then from her account, deleted my own account giving MA only one account to transfer so presumably that account will be the owner on the new Mac.

From what I have read in first linked article

" According to the small print in Apple’s Platform Security Guide, when you set up a new M1 Mac, or set one up after restoring it in DFU mode, the primary admin account created is special: it’s the Owner account of that Mac. During that inital setup, the Mac sends a request to Apple for that Mac’s signed Owner Identity Certificate (OIC). This is based on a private key generated in the Secure Enclave known as the Owner Identity Key (OIK). "

Now in your original setup of the new M4 MBP with your account

I can be wrong here so might that is with a Grain of Rock Salt

Even if you have added an additional Admin Account and removed your original Owner / Admin account

Your oldest, may not have Full Ownership privileges but should still have Admin privileges

Very untidy to say the least

Owl-53 wrote:

Your oldest, may not have Full Ownership privileges but should still have Admin privileges

Very untidy to say the least

Hopefully, since her new Mac was set up with only her account transferred by MA, she is the Owner.

Is there a way to identify the Owner account?

Your advice is much appreciated!

(Apologies to the OP for the threadjack!)

At this point I am getting way above my knowledge base and comprehension

Contents of a LocalPolicy file for a Mac with Apple silicon

On an Apple silicon Mac, the first user to set up the device becomes the "Owner" and has a secure token, which provides full administrative privileges and access to the Owner Identity Key (OIK). This ownership is crucial for managing security settings, installing software, and controlling other user accounts. You can determine if a user has owner privileges by checking their account type in System Settings > Users & Groups and verifying if they have the ability to add or manage other users and change system settings. 

Here's how to determine and manage owner privileges on an Apple silicon Mac:

1. Check User Account Type:

• Go to Apple menu > System Settings.
• Click on Users & Groups in the sidebar.
• Look for the user account you're interested in.
• If the user is an Administrator, they have owner privileges.
• If the user is a Standard user, they have limited privileges.
• If the user is a Sharing Only user, they can only access shared files. 

2. Identify the First User (Volume Owner):

• The user who first set up the Mac and configured it for their use is the Volume Owner.
• They have a secure token and can manage the device. 

3. Understanding Owner Privileges:

• Full control:
• Owner privileges include the ability to manage other users, install software, change system settings, and manage security policies. 
• Secure Token:
• The secure token is a cryptographic key that confirms the user's ownership of the Mac. 
• Owner Identity Key (OIK):
• This key is used to sign the LocalPolicy (a set of security rules) and is only accessible to the Owner. 

4. Managing Owner Privileges:

• Changing Ownership:
• If you need to change the owner, you'll need to create a new user account with administrator privileges and then potentially transfer the secure token and ownership to the new user. 
• Restricting Access:
• You can restrict access to certain files and folders by adjusting sharing and permissions settings in Finder. 
• Remote Management:
• If you need to manage the Mac remotely, you can use Remote Desktop and configure access privileges for specific users. 

Important Notes:

• On Apple silicon Macs, the user who first sets up the device becomes the initial owner and has the secure token. 
• You can't directly determine ownership based on serial number or other identifiers. 

I also had a message that an app was still active (Spotify) and choose the restart now option. now my Mac wants to sign into recovery mode and accepts my password but does not move on from the Mac OS recovery screen after accepting password. When rebooted, still asks to sign in to recovery, with same results. I have two Macs. Downloaded this os update on newer Mac. It says update did not complete due to adobe being open. Adobe is not open....

Thanks to a respected contributor @leroydouglas

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

dscacheutil -q group -a name admin

If you forgot your Mac login password - Apple Support

👍. 🦉

Holly Batman

Let me think on this and get back to you

Passcodes and passwords - Apple Support (CA)