Install Exchange 2013 Cumulative Update 8

On March 17 Microsoft released the 8th Cumulative Update for Exchange Server 2013, 98 days after the release of CU7 which is nicely in line with the quarterly release cadence of Cumulative Updates. This Cumulative Update is called CU8, not a word about Service Pack 2, so SP1 still continues to be the officially supported Service Pack.

There are some new features in CU8 that are worth noticing.

  • With CU8 there are improvements for mobile clients in a Hybrid Configuration. When a Mailbox is moved the Outlook client will automatically detect and reconfigure accordingly. This was not the case with Mobile clients. This behavior has changed in CU8. When a mobile client connects the local Exchange server and the Mailbox is moved to Exchange Online an additional check for the TargetOWAUrl on the Organization Relationship object is performed. This will return an HTTP/451 redirect to the mobile client which in turn will be redirected to this new URL. This feature will be available to all EAS compatible devices that can handle the HTTP/451 redirect option. Unfortunately this feature is only available for onboarding customers (i.e. to Office 365) and not for offboarding (from Office 365) customers.
  • There an improved migration for Public Folders migration, now supporting batch migrations. This is faster (supports multiple jobs), more reliable and provides an easier migration management.
  • CU8 supports viewing calendar and contact types of modern Public Folders in OWA

Besides these new features there’s a ton of hotfixes in CU8. More information can be found in Microsoft knowledgebase article KB3030080, CU8 itself can be downloaded from the Microsoft Download site., the accompanying CU8 UM Language packs are available as well. At the same time Microsoft released Update Rollup 9 for Exchange 2010 SP3 and Update Rollup 16 for Exchange 2007 SP3.

Installing CU8

This question pops up on a regular basis…. When installing CU8, there’s no need to install a previous build and then run CU8. This is not only true for CU8 but for every Cumulative Update. You can install Windows Server 2012 R2 and install Exchange 2013 CU8 and you’re done.

Upgrading an existing Exchange 2013 server to CU8 is not that difficult. Please note that only upgrading from versions n-2 is officially supported, which means upgrading from CU6 or CU7. You can upgrade from earlier versions of Exchange 2013 and most likely this will work, but if you run into issues and need help from Microsoft you might be charged with a regular support call.

For a Hybrid Environment you always need to be running the latest version of Exchange 2013 which means you should be upgrading from CU7 to CU8 when running Exchange 2013 on-premises.

Upgrading from an earlier version of Exchange 2013 is relatively simple. You can upgrade the Active Directory using the regular commands:

Setup.exe /prepareSchema /IAcceptExchangeServerLicenseTerms

Setup.exe /prepareAD /IAcceptExchangeServerLicenseTerms

Setup.exe /prepareDomain /IAcceptExchangeServerLicenseTerms


You can also use PowerShell to check the schema version using the following commands:

$root = [ADSI]"LDAP://RootDSE"
$m = [ADSI]("LDAP://" + "CN=ms-Exch-Schema-Version-Pt," + $root.schemaNamingContext)

For a complete list of version numbers and schema changes (in Exchange 2013) you can visit the following Microsoft site:

Upgrading the Exchange server can be achieved using the following command:

Setup.exe /mode:upgrade /IAcceptExchangeServerLicenseTerms

Please note that upgrading an Exchange 2013 server to the latest version is very similar to reinstalling an Exchange 2013 server. Any customization on the Exchange 2013 server is lost and you have to customize your servers again. Also when an upgrade fails there’s a distinct possibility you will lose your entire server and have to switch gear to a disaster recovery scenario. There’s no roll-back option after an upgrade to the latest (or any) version of Exchange 2013.

So please make sure you thoroughly test Exchange 2013 CU8 before bringing it into production.

Upgrading DAG members

When upgrading Exchange 2013 DAG members you have to put the Exchange 2013 server into maintenance mode before upgrading them. You can use the following PowerShell commands to put the Exchange 2013 DAG member into maintenance mode:

$Computer = $ENV:ComputerName
Set-ServerComponentState $Computer -Component HubTransport -State Draining -Requester Maintenance
Redirect-Message -Server $Computer -Target

# Prevent DAG member becoming PAM
Suspend-ClusterNode $Computer

# Move all Mailbox Databases and prevent hosting copies on current server
Set-MailboxServer $Computer -DatabaseCopyActivationDisabledAndMoveNow $True
Set-MailboxServer $Computer -DatabaseCopyAutoActivationPolicy Blocked

# Put the Exchange 2013 server in Maintenance Mode:
Set-ServerComponentState $Computer -Component ServerWideOffline -State Inactive -Requester Maintenance

You can verify if the server is actually running in maintenance mode by using the following command in PowerShell:

Get-ServerComponentState $Computer | ft Component,State –Autosize


When checking the load balancer you can see that the Exchange 2013 server is marked as ‘offline’ due to the maintenance mode:


You can now safely upgrade the server to CU8 using the commands mentioned earlier.

Note. When running a dedicated Exchange 2013 CAS server and you want to put in maintenance mode you can use the following commands in PowerShell:

Set-ServerComponentState $Server -Component ServerWideOffline -State Inactive -Requester Maintenance
Restart-Service MSExchangeFrontEndTransport

When the DAG member is successfully upgraded you can get the Exchange 2013 servers out of maintenance mode using the following commands in PowerShell:

$Computer = $ENV:ComputerName
Set-ServerComponentState $Computer -Component ServerWideOffline -State Active -Requester Maintenance
Resume-ClusterNode $Computer

Set-MailboxServer $Computer -DatabaseCopyActivationDisabledAndMoveNow $False
Set-MailboxServer $Computer -DatabaseCopyAutoActivationPolicy Unrestricted

Set-ServerComponentState $Computer -Component HubTransport -State Active -Requester Maintenance

Restart-Service MSExchangeTransport
Restart-Service MSExchangeFrontEndTransport

Note. To get a dedicated Exchange 2013 CAS server out of maintenance mode you can use the following commands in PowerShell:

$Computer = $ENV:ComputerName
Set-ServerComponentState $Computer -Component ServerWideOffline -State Active -Requester Maintenance
Restart-Service MSExchangeFrontEndTransport

To verify if all services are available again you can use the following command:

Get-ServerComponentState $Computer | ft Component,State –Autosize

All Components should be marked as Active. An exception can be the ForwardSyncDeamon and ProvisioningRpc components which might be marked as Inactive. These are Exchange Online specific components so this can be ignored for on-premises deployments of Exchange 2013 CU8.



Exchange 2013 CU8 was released on March 17, 2015 and at the moment of writing the latest version of Exchange 2013. From a supportability point of view CU8 and CU7 are supported, and so are the upgrade paths. Upgrading from earlier versions of Exchange 2013 is not formally supported, but in this case it is not tested but in 99.9% of all upgrades it should work fine. If you run into issues you can call Microsoft for support and you might be charged for one incident, depending of the type of issue you’re facing.

Upgrading to Exchange 2013 CU8 is fairly easy, when upgrading DAG members you have to put the DAG members in maintenance mode before upgrading as described in this article. Please note that upgrading is basically a reinstall of the application, so all customizations are lost during the upgrade. Also, there’s no roll-back option after upgrading to CU8

As usual, please take your time for testing and evaluating Exchange 2013 CU8 before bringing this build into production.

8 thoughts on “Install Exchange 2013 Cumulative Update 8”

    1. Hi Francois,
      This is not supported for a long term situation of course, but for an upgrade process you should be fine. However you should try to keep the CU5/CU8 coexistence as short as possible. The DAG will continue to work, no problem.


  1. It’s a well known fact that any customizations are lost when installing a CU, but in the Exchange 2013 world, what is considered a “customization”? If there are Lync/OWA changes to the OWA web.config file, are those lost? Do I lose my Receive connectors for the server that’s being upgraded? What about certificates? Is there a document somewhere that might detail some of the things that will be overwritten, or is it an install-it-and-see-what-breaks scenario?


    1. Hi,
      I don’t have such a document, but my experience is that all normal config changes that are made to the Exchange server like SSL Certificates, Receive Connectors, SMTP Queue Database location etc are preserved during an upgrade. Real customization like editing a web.config file or changing the logon page for OWA are lost.
      Changes to config files need to be recreated. Please don’t replace config files with previous version. I’ve seen customers do this and getting into lots of trouble because of (undocumented) changes that Microsoft makes in config files. Replacing config files with previous ones is something I consider as a ‘worst practice’.
      Thanks – Jaap


  2. Thanks for the article.
    I think this line in DAG member draining script may fail because of the undefined $Server varible :
    Redirect-Message -Server $Server -Target


    1. Hi Chris,

      In this blogpost ( in the Q&A section you’ll see this:
      Q: How long is a CU supported?
      A: A CU will be supported for a period of three (3) months after the release date of the next CU. For example, if CU1 is released on 3/1 and CU2 is released on 6/1, CU1 support will end on 9/1.

      Service Pack 1 is a different story though. SP1 is supported 12 months after the release of the next Service Pack (i.e. SP2), but since this isn’t available, SP1 is still supported.
      When you have a hybrid environment with Exchange Online you should be on the latest available CU to be supported.

      I’ll monitor the support statement when a new Cumulative Update and focus a bit on this. Thanks for letting me know.


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