Issue: You need to prepare the Active Directory Domain and Schema for the installation of Exchange 2013 CU21.
Background: Exchange 2013 CU7(potentially CU10 w/organization object) was the last version of Exch 2013 to contain a schema upgrade.
Action Plan: Review the scenarios below to determine whether a schema upgrade is required in addition to domain upgrade, then follow the appropriate steps outlined below.
The following scenarios require an AD Schema upgrade (/PrepareSchema) and AD Domain Upgrade (/PrepareAD):
– new installations of Exchange 2013 (any version including CU21)
– upgrading to CU7 through CU21 from CU6 or older
– upgrading to SP1 (CU4), CU5 or CU6 from any prior version
Action: if you fall into any of the above scenarios, then follow all steps in the solution section below
The following scenario require only an AD Domain upgrade (/PrepareAD):
– You’re running CU7 or newer and upgrading to CU21
Action: follow solution section below skipping steps 4-5
Solution: Perform AD Schema and Domain Preparation for Exchange 2013 CU21 using the following step-by-step instructions:
1) If you haven’t already, download the latest version of Exchange 2013.
2) Next, verify AD health by running DCDIAG and REPADMIN /SYNCALL from a run-as-administrator command prompt on your DC’s. If issues are found here is a good starting point to troubleshoot active directory.
3) Copy the download to an easily accessible folder on one of your Domain Controllers or Exchange servers (for example C:\Exch2013CU21\download). Run the downloaded file in order to extract the installation files, extract them to c:\Exch2013CU21
4) open a command prompt as administrator on the DC and prepare the AD schema using the following command from a ‘run-as-administrator’ command prompt:
setup.exe /PrepareSchema /IAcceptExchangeServerLicenseTerms
Note: your account must be a member of Schema Admins
5) Once the schema upgrade is complete, run ‘repadmin /showreps’ from the command prompt to make sure AD replication has completed and any schema mismatch errors have gone away (they will eventually go away on their own). I also recommend running DCDIAG again to make sure it passes before moving on.
6) Prepare AD by running the following command from a ‘run-as-administrator’ command prompt:
setup.exe /PrepareAD /IAcceptExchangeServerLicenseTerms
7) Repeat the AD health checks outlined in Step 5 again, again it may take awhile for the schema mismatch error to go away (this error is normal).
8) If you are installing Exchange 2013 for the first time in your environment, here are step-by-step instructions to install Exchange 2013 Cumulative Updates. If you already have Exchange 2013 installed, here are instructions to Upgrade your existing Exchange 2013 server to the latest Cumulative Update.
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