Squeaky Clean Install of Ventura 13.2.1?

It is in principle very simple to restore some normalcy, and it does not require reinstalling the OS completely, because the OS itself is in a sealed read only partition.

1) Make two backups of your data, at least of them in the form of a Time Machine

2) In System Settings->General, click Transfer or Reset, then Click "Erase All Content and Settings..."

3) After the system restarts (as if it were starting for the first time), you will be asked if you want to transfer your data. Choose "From another mac, drive or Time Machine backup"; and NOW VERY IMPORTANT: transfer ONLY the user accounts that you want, and do NOT transfer "applications", "settings" or "other files".

Follow on.

It would require making a Bootable Installer of Ventura and then changing the About Startup Security Utility on a Mac with the Apple T2 Security Chip - Apple Support Before attempting the Bootable Installer

Added inför but the Partition Thing is still an issue

Use Disk Utility to erase a Mac with Apple silicon.

On a Multi User Account Setup, I am not sure if Migrating ONLY an known Non Polluted Account ADMIN would work ?

Then, in that specific account, create the additional accounts ONLY.

Allow them to commence Rebuilding the account with the Software that s required to become functional again.

Links below

Change Users & Groups settings on Mac - Apple Support (CA)

Move content to a new Mac - Apple Support (CA)

Q - " Once I had ruled out a hardware issue I just booted up in the problematic OS, and had enough time to click the "-" button in Disk Utility when "test" was selected and the test volume/partition is now gone. So (I think) I am back to my (broken) baseline. "

A - Just to be on the Safe Side

A - Would to run the Terminal Command below and post back the text output

diskutil apfs list

A - While at it - a screen shot from Disk Utilities >> View >> Show ALL Devices ( preferred without Externals Attached )

image below as example

Q - " I set up a test partition with a clean install of Ventura and it ran perfectly from that, so am thinking it is a software issue."

A - Partition or Volume that may complicate this on Apple Silicon Computer.

A - A Volume can be removed from Disk Utilities but a Separate Partition my require Nuking the Entire Drive to gain back the Space as Usable again

CharPatton wrote:

(As I understand it, if I use migrate or restore options from my backup disk, this will indeed put all 8 log-ons back on and all the personal data, but will also copy any "problematic" system software back over as well :( )

Your understanding is correct.

To compare

Below

diskutil apfs list

APFS Containers (3 found)

|

+-- Container disk3 127E50BD-2D64-4B02-9371-E65320035185

    ====================================================

    APFS Container Reference:     disk3

    Size (Capacity Ceiling):      494384795648 B (494.4 GB)

    Capacity In Use By Volumes:   28640227328 B (28.6 GB) (5.8% used)

    Capacity Not Allocated:       465744568320 B (465.7 GB) (94.2% free)

    |

    +-< Physical Store disk0s2 0B0021D3-AB20-47B7-818F-68ACC7769640

    |   -----------------------------------------------------------

    |   APFS Physical Store Disk:   disk0s2

    |   Size:                       494384795648 B (494.4 GB)

    |

    +-> Volume disk3s1 F2658F62-F02D-4AD4-929E-00307C204B6B

    |   ---------------------------------------------------

    |   APFS Volume Disk (Role):   disk3s1 (System)

    |   Name:                      Macintosh HD (Case-insensitive)

    |   Mount Point:               Not Mounted

    |   Capacity Consumed:         8946552832 B (8.9 GB)

    |   Sealed:                    Yes

    |   FileVault:                 No (Encrypted at rest)

    |   |

    |   Snapshot:                  7F83C60F-C7FE-4E03-B88A-AF338EA2B683

    |   Snapshot Disk:             disk3s1s1

    |   Snapshot Mount Point:      /

    |   Snapshot Sealed:           Yes

    |

    +-> Volume disk3s2 0219C089-6C94-4617-A477-80DD00886DED

    |   ---------------------------------------------------

    |   APFS Volume Disk (Role):   disk3s2 (Preboot)

    |   Name:                      Preboot (Case-insensitive)

    |   Mount Point:               /System/Volumes/Preboot

    |   Capacity Consumed:         4833214464 B (4.8 GB)

    |   Sealed:                    No

    |   FileVault:                 No

    |

    +-> Volume disk3s3 0B9D2868-9DCD-4CE5-B709-8C2167BB87A4

    |   ---------------------------------------------------

    |   APFS Volume Disk (Role):   disk3s3 (Recovery)

    |   Name:                      Recovery (Case-insensitive)

    |   Mount Point:               Not Mounted

    |   Capacity Consumed:         786108416 B (786.1 MB)

    |   Sealed:                    No

    |   FileVault:                 No

    |

    +-> Volume disk3s5 C06FDD00-7C0A-46ED-8656-C80A91560802

    |   ---------------------------------------------------

    |   APFS Volume Disk (Role):   disk3s5 (Data)

    |   Name:                      Data (Case-insensitive)

    |   Mount Point:               /System/Volumes/Data

    |   Capacity Consumed:         13908729856 B (13.9 GB)

    |   Sealed:                    No

    |   FileVault:                 No (Encrypted at rest)

    |

    +-> Volume disk3s6 76A39862-78F5-4E9A-98F6-41B9CCCD4E92

        ---------------------------------------------------

        APFS Volume Disk (Role):   disk3s6 (VM)

        Name:                      VM (Case-insensitive)

        Mount Point:               /System/Volumes/VM

        Capacity Consumed:         20480 B (20.5 KB)

        Sealed:                    No

        FileVault:                 No

p.phillips@Ps-MacBook-Air---M2 ~ %