Recently when attempting to perform an Azure AD Join with a Windows 10 v1511 computer I got the following error:
Something went wrong. The device is already enrolled. You can contact your system administrator with the error code 8018000a.
That didn’t make sense because I had recently disjoined the computer from Azure AD. I could find no reference to the object in the Azure portal either.
A Bingoogle search yielded only one relevant result… the ConfigMgr client is installed.
I knew this wasn’t the case. So… read the error again. “the device is already enrolled”. Checking Settings -> Accounts -> Work Access revealed the obvious: the computer was still being managed via OMA-DM (Intune), but associated with a different user.
Ok. Log off, then back on as the other administrator account.
Navigate back to Work Access and sure enough, the MDM enrollment was there. Un-enroll and bingo, Azure AD Join worked!