Hi Experts,

We are using Microsoft Exchange Server 2013 and trying to install Cumulative Update 18. While trying to extend the Active Directory Schema, we are getting below error when running given command on any Exchange servers.

Forest Name: abc.com

Domain Name: child.abc.com

Exchange Version: Microsoft Exchange Server 2013 

Current CU Version: Cumulative Update 5

Indent to Install: Cumulative Update 18

Note: Our exchange server are falls under child.abc.com and we are using Enterprise and Schema Admin to run commands.

Error Details:------------------------------------------------------------------------------------

D:\Exchange2013CU18>Setup.exe /PrepareSchema /IacceptExchangeServerLicenseTerms

Microsoft Exchange Server 2013 Cumulative Update 18 Unattended Setup

Copying Files...
File copy complete. Setup will now collect additional information needed for
installation.

Performing Microsoft Exchange Server Prerequisite Check

    Prerequisite Analysis                                     FAILED 
     The Active Directory schema isn't up-to-date, and this user account isn't a member of the 'Schema Admins' and/or 'Enterprise Admins' groups.
     For more information, visit: http://technet.microsoft.com/library(EXCHG.150)/ms.exch.setupreadiness.SchemaUpdateRequired.aspx

     Setup encountered a problem while validating the state of Active Directory:
Exchange organization-level objects have not been created, and setup cannot create them because the local computer is not in the same domain and site as the schema master.  Run setup with the /prepareAD parameter on a computer in the domain ABC.COM and site ABC-HQ, and wait for replication to complete.  See the Exchange setup log for more information on this error.
     For more information, visit: http://technet.microsoft.com/library(EXCHG.150)/ms.exch.setupreadiness.AdInitErrorRule.aspx

     The forest functional level of the current Active Directory forest is not Windows Server 2003 native or later. To install Exchange Server 2013, the forest
functional level must be at least Windows Server 2003 native.
     For more information, visit: http://technet.microsoft.com/library(EXCHG.150)/ms.exch.setupreadiness.ForestLevelNotWin2003Native.aspx

     Either Active Directory doesn't exist, or it can't be contacted.
     For more information, visit: http://technet.microsoft.com/library(EXCHG.150)/ms.exch.setupreadiness.CannotAccessAD.aspx

The Exchange Server setup operation didn't complete. More details can be found
in ExchangeSetup.log located in the <SystemDrive>:\ExchangeSetupLogs folder.