The Active Directory Domain Services Installation Wizard (Dcpromo.exe) was unable to convert the computer account %1 to an ...

The Active Directory Domain Services Installation Wizard (Dcpromo.exe) was unable to convert the computer account %1 to an Active Directory Domain Controller account.

Verify that the user running Dcpromo.exe is granted the "Enable computer and user accounts to be trusted for delegation" user right in the Default Domain Controllers Policy. 

For more information, see the resolution section of http://go.microsoft.com/fwlink/?LinkId=178406.

The error was: