In this post, you’ll learn more about the Error CERTSRV_E_SUBJECT_UPN_REQUIRED – 0x8009480D that is returned when working with the COM-based APIs in Win32
Win32 COM Error
CERTSRV_E_SUBJECT_UPN_REQUIRED – 0x8009480D
Win32 COM Error Error Description
The UPN is unavailable and cannot be added to the Subject Alternate name.