## TL;DR
A previous management profile is still installed, and macOS allows only one MDM enrollment. Remove the old profile from System Settings, confirm it is gone, then enroll again.

## The query
```text
mdm enrollment failed: "an existing MDM profile was found" on macos
```

## Use this when
- macOS enrollment fails with the existing MDM profile message
- a Mac was reimaged but kept its old profile
- moving a Mac from one MDM to another

## Not for
- MDM server not reachable errors
- enrollment credential or invitation failures
- Apple Business Manager assignment problems

## Steps
1. Open System Settings, then General, then Device Management, and list the installed profiles. Expected output: the stale management profile is visible.
2. Remove the old MDM profile, providing admin credentials if prompted. Expected output: the profile list no longer shows the old enrollment.
3. Verify removal with the profiles command to confirm no MDM payload remains. Expected output: no MDM profile is reported.
4. Start enrollment with the new MDM invitation or enrollment URL. Expected output: the new profile installs and the Mac checks in.
5. Confirm in the new MDM console that the device is enrolled and compliant. Expected output: the device record appears with a recent check-in.

## Applies to
macOS Ventura and later, Jamf Pro, Mosyle, Kandji, or any MDM, Apple Business Manager.

## Variant phrasings
### Profile remove button is greyed out
The profile is non-removable; erase the Mac or use the old MDM to release it first.

### Old profile returns after removal
Automated Device Enrollment re-pushes it; release the device in Apple Business Manager first.

## Why it happens
macOS enforces a single MDM authority per device. Reimages and tenant moves often leave the old profile behind, and the new enrollment refuses to proceed until it is gone.

## Edge cases
- User-approved MDM on older macOS needed manual approval; the flow differs before Ventura.
- If the old MDM is decommissioned, an erase may be the only path to clear a non-removable profile.
- Document the serial before erasing; you will need it to reassign in Apple Business Manager.

## Provenance

Resolved from the public thread: https://vectle.com/posts/pst_3eckmbbCU8zTd-KcH_8pmQ