XADM: Unable to Update the Schema on the Schema Owner

When you try to modify the schema by using the ADSI Edit utility or the Active Directory Schema Microsoft Management Console (MMC) snap-in on a domain controller that is the schema Flexible Single Master Operation (FSMO) owner, you may receive the following error message: When you try to modify the schema by using the Lightweight Directory Protocol (LDP) tool (this is an Active Directory Support Tool and is available on the Windows 2000 Server compact disc in the Support\Tools folder), you may receive the following error message: When you try to modify the schema by using the Ldifde utility (the ldifde -i command), you may receive the following error message:

This issue can occur because even though the domain controller is the schema owner, by default you cannot edit the schema. You must enable the The Schema may be modified on this Domain Controller option in the Active Directory Schema MMC snap-in to modify the schema.

To resolve this issue, enable schema modification:

1. Click Start, and then click Run. In the Open box, type mmc, and then click OK.
2. When MMC starts, click Add/Remove Snap-in on the Console menu.
3. Click Add.
4. Click Active Directory Schema, click Add, and then click Close.
5. Click OK.
6. Right-click Active Directory Schema, and then click Operations Master.
7. Click The Schema may be modified on this Domain Controller.
8. Click OK.

When you enable or disable the The Schema may be modified on this Domain Controller option in the Active Directory Schema MMC snap-in, it changes the value of the following registry key:

Gaining Access to the Active Directory Schema MMC Snap-In

By default, the Active Directory Schema MMC snap-in is not listed as an available snap-in. If the Active Directory Schema MMC snap-in is not available, perform the following steps to enable it:

1. Click Start, and then click Run.
2. In the Open box, type regsvr32 schmmgmt.dll, and then click OK.

A dialog box that states "DllRegisterServer in schmmgmt.dll succeeded" is displayed, and the Active Directory Schema MMC snap-in is displayed in the list of available snap-ins.

How Exchange 2000 Server Updates the Schema

When Exchange 2000 Server is installed in a Windows 2000 Server forest, Exchange 2000 Server needs to modify the schema. Exchange 2000 Server connects to the schema FSMO owner, and locates the value of the following registry key: If the value is set to 1 (TRUE), Exchange 2000 Server does not modify the value. If the value is set to 0 (FALSE), Exchange 2000 Server changes the value to 1, makes the schema modifications, and then changes the value back to 0.