Ensure that the forest functional level is Windows Server 2003 or higher

Administrative credentials

Any domain user can verify that the current forest functional level is Windows Server 2003 or higher. To raise the forest functional level, you must be either a member of the Domain Admins group in the forest root domain or a member of the Enterprise Admins group.

To ensure that the forest functional level is Windows Server 2003 or higher

1. Open Active Directory Domains and Trusts.
2. In the console tree, right-click the name of the forest, and then click Properties.
3. Under Forest functional level, verify that the value is Windows Server 2003 or Windows Server 2008.
4. If it is necessary to raise the forest functional level, in the console tree, right-click Active Directory Domains and Trusts, and then click Raise forest functional level.
5. In Select an available forest functional level, click Windows Server 2003, and then click Raise.