In this article I will demonstrate the step by step process for installing cumulative updates and service packs for Exchange Server 2013.

The steps for installing cumulative updates and service packs on Exchange 2013 are:

  1. Prepare by downloading update files, checking backups, and reviewing known issues
  2. Update mailbox and multi-role servers in the internet-facing sites
  3. Update client access servers in the internet-facing sites (if any)
  4. Update Exchange 2013 servers in any remaining internal sites (if any)
  5. Update Edge Transport servers (if any)
  6. Perform health checks and rebalancing of servers

Preparation Tasks

Before installing any cumulative updates you should:

  • Download the CU or Service Pack setup file from the Microsoft Download Center (do not download from third party sites) and extract it to a folder on each server. You can download the latest cumulative update and upgrade an Exchange 2013 server to the latest version in one update. You do not need to install all of the cumulative updates released between your current version and the latest version.
  • Take a confirmed backup of Active Directory.
  • Take a confirmed backup of your existing Exchange 2013 servers and databases.
  • Have documented any customizations such as OWA, config files on servers, registry changes, Lync integration, or third party add-ons.
  • Review this known issue with receive connectors that can cause upgrades to fail, leaving servers in a non-operational state.
  • Verify that your Exchange SSL certificates have not expired.
  • Check the Exchange Supportability Matrix and verify that you are maintaining the .NET Framework on your servers to remain compatible with Exchange.

Installing Cumulative Updates and Service Packs

Cumulative updates and Service Packs should be installed in the internet-facing site first, before installing in other sites in the organization.

  • The first servers to be updated in a site are the Mailbox servers.
  • The Client Access servers are updated second.
  • Edge Transport servers can be updated last.

If you have multi-role CAS/MBX servers installed then setup updates the roles in the correct order anyway, and you should simply start with the internet-facing servers.

During the deployment of a cumulative update within a site that contains load-balanced Client Access server or Database Availability Group members there will be a period where servers are not at exactly the same version. Although this is expected and supported, it is not supported to stay in that state for a long period of time.

In other words, you should plan to update all DAG members within a short period of time, and not allow them to run at different versions for days, weeks or months.

Updating Mailbox Servers

Mailbox servers in a multi-server environment, whether installed as standalone or as a multi-role server, should be placed into maintenance mode before installing the cumulative update.

Note that the redirect target server must be provided as a fully qualified domain name.

If the server is a DAG member proceed to the next section which contains additional steps for DAG members, otherwise put the server into maintenance mode with the following command.


Exchange MVP Michael Van Horenbeeck has published a script for automating the process of starting and stopping maintenance mode.

Updating Mailbox Servers that are Database Availability Group Members

In addition to placing Mailbox servers in maintenance mode any DAG members also need to have active mailbox databases moved to another DAG member, and be blocked from activation while the cumulative update is being installed.

Suspend the DAG member from the cluster.

Disable database copy activation.

Review the existing database copy auto activation policy, so that you can return it to the same configuration after you’ve completed the upgrade.

Set the auto activation policy to “Blocked”. If the policy is already set to “Blocked” then there is no action required.

Put the server into maintenance mode.


Taking Servers Out of Maintenance Mode

To take the server out of maintenance mode after the upgrade the process is reversed. Make sure that you return the database auto activation policy to the original setting if it was not “Unrestricted”.


Exchange MVP Michael Van Horenbeeck has published a script for automating the process of starting and stopping maintenance mode.

Updating Load-Balanced Client Access Servers

If you are running load-balanced Client Access servers in a site then you should configure the load balancer to remove the server from the pool of hosts, and allow any existing connections to close, before you install the cumulative update.

The exact steps for this will depend on the load balancing solution that you use, and you should refer to your vendor documentation for those.

As each Client Access server is updated join it to the pool again and then repeat the process for the next server.

Active Directory Preparation Tasks

Some cumulative updates will include Active Directory schema changes. In those cases the following steps will be required.

Note: The AD preparation tasks are not required to be run separately to the upgrade of Exchange, unless in circumstances where you need to separate the tasks to different teams with different permissions, or if you have a multi-domain forest and want to control the AD changes.

Before applying the schema update follow the steps provided by Michael B Smith to retrieve the existing Exchange schema version, so that you can compare it before and after the AD preparation steps have been completed to verify that the schema update was applied.

  1. Run setup.exe /PrepareSchema /IAcceptExchangeServerLicenseTerms (requires Enterprise Admins and Schema Admins permissions, and must be performed in the same AD Site as the Schema Master on a server with the RSAT-ADDS-Tools feature installed – the Schema Master itself would meet these requirements)
  2. Run setup.exe /PrepareAD /IAcceptExchangeServerLicenseTerms
  3. Run setup.exe /PrepareDomain /IAcceptExchangeServerLicenseTerms in each domain in your forest that contains Exchange servers or mailboxes

When the Active Directory changes have been applied, on each server run the upgrade.

Upgrading the Servers

Cumulative updates can be applied using either the command line or graphical setup, whichever you prefer. Both options are demonstrated below.

  • Follow the pre-installation processes outlined earlier in this article depending on the server roles installed.
  • Do not run the upgrade from the Exchange Management Shell as this will cause it to fail due to locked files. Run the upgrade from an elevated cmd prompt.
  • If you receive a warning that the Office Filter Pack is not installed this can be ignored, as it is not a required component for Exchange Server 2013.
  • Set the PowerShell execution policy on each server being upgraded to Unrestricted, as this may sometimes cause issues with update. Refer to KB981474.

Caution: a cumulative update is a full reinstall of Exchange Server 2013. If it is interrupted, or fails part way through the installation, you may need to perform a server recovery. There is also no way to uninstall a cumulative update.

Note: Exchange 2013 cumulative updates stop the “Microsoft Exchange FrontEnd Transport” and “Microsoft Exchange Transport” services during the pre-requisites check. If you do not proceed with the installation you will need to manually restart the Microsoft Exchange Transport service.

Upgrading Using the Command Line

In an elevated command prompt run the following command from the location where you extracted the cumulative update files.

The command prompt window will display the progress as the upgrade proceeds. The upgrade itself is a lengthy process so you should allow plenty of time for each server.

After the cumulative update has been install restart the server if prompted to do so.

If you had placed the server into maintenance mode then you can run the commands or the script for stopping maintenance mode after the installation is finished (refer to the notes above).

Upgrading Using the Graphical Setup

From the location that you extracted the cumulative update files run Setup.exe. It is recommend to allow setup to connect to the internet and check for updates.


When the update check has completed click Next to continue.


Setup will begin copying files. This can take several minutes depending on your server’s performance capacity.


Setup will detect that this is an upgrade installation.


You will need to accept the license agreement each time you upgrade a server.


Setup will perform a pre-requisites check. If any pre-requisites are not met setup will stop and warn you about them, otherwise you will be able to proceed with the upgrade.


The upgrade itself is a lengthy process and you may find that some steps appear to have hung with no progress. This may be a bug with the graphical setup, whereas the command line setup will typically show the percentage progress as it goes.


When setup is complete you will be prompted to restart the server if required.


After the cumulative update has been install restart the server if prompted to do so.

If you had placed the server into maintenance mode then you can run the commands or the script for stopping maintenance mode after the installation is finished (refer to the notes above).

Post-Installation Tasks

After deploying an Exchange 2013 cumulative update there are a number of post-installation tasks that may be required.

Rebalance the Database Availability Group

After you’ve updated all of your DAG members there is a good chance that the active databases will not be evenly distributed across the DAG, or won’t be on their first activation preference. This process is the same for Exchange 2013 as it is for Exchange 2010.


Restoring Customizations

After you have completed updating your servers you will need to re-apply any customizations that you had documented during the preparation steps above.

Verifying Server Health

Here are some suggestions for health checking your Exchange 2013 servers after applying updates.

  1. Check the cluster nodes are all up – verify that you have not left any DAG members suspended in the cluster by running the Get-ClusterNode cmdlet on one of the DAG members.
  2. Test service health – use the Test-ServiceHealth cmdlet to verify that all required services are running on each server.
  3. Test MAPI connectivity to every database – use the Test-MAPIConnectivity cmdlet to verify that all databases are mounted and accessible.
  4. Check the database copy status for DAGs – use the Get-MailboxDatabaseCopyStatus cmdlet to verify that all database copies, copy/replay queues, and content indexes are healthy.
  5. Test replication health for DAGs – use the Test-ReplicationHealthcmdlet on each DAG member to verify replication health is good.
  6. Check the database activation policy for each Mailbox server – verify that each Mailbox server that is in a DAG has the correct database activation policy for your environment.
  7. Check server component status – use Get-ServerComponent to verify that you have not left any servers in maintenance mode.
  8. Run Exchange Analyzer to check for best practices compliance.

You can also use Test-ExchangeServerHealth.ps1 to review the health of your environment.


Thanks to Exchange MVPs Tony RedmondJeff GuilletMichael B Smith, and Michael Van Horenbeeck for sharing their notes and experiences with the cumulative update process.

Abdulsalam Garba

The author Abdulsalam Garba

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