How to solve the Error “The device is already joined. You can contact your system administrator with the error code 8018000a”

Causes: - The error is caused when the device has been joined to Azure AD by another account. This may be since the machine was being used by other users previously and was joined with other accounts in use or the current user if the machine has only been used by a single user.

Pre-checks

Some things to verify before processing:
 – The device should NOT be in your Intune portal https://portal.azure.com/#blade/Microsoft_Intune_Devices

– Verify that the computer is not in fact joined. Run this command in an elevated prompt: dsregcmd /status

The above screenshot shows that the device is AzureAdJoined

 

 

SOLUTION 1: 

Use these steps to remove the other work or school account.

  1. Sign out of Windows, then sign in by using the other account that has enrolled or joined the device. (Note that the other account is the account that joined the device from the machine on a machine that different users have logged in to) 
  2. Go to Settings > Accounts > Work Access, then remove the work or school account.
  3. Sign out of Windows, then sign in by using your account.
  4. Enroll the device in Intune or join the device to Azure AD.

 

SOLUTION 2: Incase you cannot login into the other account that joined the device

Remove the traces from “ongoing Azure AD join” or already joined Azure AD.

You can do this by deleting the GUIDS from the registry editor by going to HKEY\LOCAL MACHINE\SOFTWARE\MICROSOFT\Enrollments

Make sure to NOT delete Context, Ownership, Status and ValidNodePaths.

 

If you expand one GUID after the other you will find the specific account and the join information. Once you have deleted the GUIDs excluding context, Ownership, status and ValidNodePaths proceed and join the device to Azure AD