How to disable the Subject Alternative Name for UPN mapping

Original KB number:   4043463
Applies to:   Supported versions of Windows Server and Windows Client

User principal name (UPN) mapping is a special case of one-to-one mapping used in Active Directory. This article describes how to use an explicit mapping instead of UPN mapping by disabling the subject alternative name (SAN) through Registry Editor. Performing the following steps will allow the use of an explicit mapping by ignoring the SAN extension of a deployed client certificate.


  1. Open Registry Editor.
  2. Go to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Kdc\UseSubjectAltName.
  3. Right-click UseSubjectAltName, select Modify Binary data, and then set the Value data to 0.


The value of the UseSubjectAltName registry key must be set to 0 on all key distribution centers (KDC) for the domain.



You must also perform steps on the client-side if the following conditions are met:

  • Client certificate mapping (AltSecID) is used.
  • A UPN is used in the SAN extension of a client certificate.
  • No domain hint is used.

Here's how to disable the SAN for the UPN mapping on the client-side:

  1. Open Registry Editor.
  2. Go to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa\Kerberos\Parameters.
  3. Press and hold (right-click) Parameters, select New > DWORD (32-bit) Value, and then name it UseSubjectAltName. Double-click it, set the Value data to 0, and then press Enter.


For more information about SAN or UPN mapping, see smart card logon flow in Certificate Enumeration.