Exchange 2013 CU13 Released

Exchange 2013 CU13 has been released to the Microsoft download centre!  Exchange 2013 has a different servicing strategy than Exchange 2007/2010 and utilises Cumulative Updates (CUs) rather than the Rollup Updates (RU/UR) which were used previously.    CUs are a complete installation of Exchange 2013 and can be used to install a fresh server or to update a previously installed one.  Exchange 2013 SP1 was in effect CU4, and CU13 is the ninth post SP1 release.


Exchange 2013 CU13 Download


This is build 15.00.1210.003 of Exchange 2013 and the update is helpfully named Exchange2013-x64-cu13.exe.  Which is a great improvement over the initial CUs that all had the same file name!  Details for the release are contained in KB 3135743.

Whether or not your AD Schema needs to be updated depends upon your initial Exchange 2013 version.  This will dictate if the AD Schema needs to be modified.  Check the values as noted in this post.  There may be additional RBAC definitions, so PrepareAD should be executed prior to installing CU13.  If setup detects that PrepareAD is required it will be automatically executed if the account running setup has the necessary permissions.  This was an issue discussed in the MessageCopyForSentAsEnabled  post


Updates Of Particular Note

Exchange 2013 CU13 adds support for .NET framework 4.6.1.  Exchange should be upgraded, and placed into maintenance mode prior to installing .NET 4.6.1 onto the Exchange server.  Note that .NET 4.6.1 will replace the existing 4.5.2 install.  There are hotfixes required in addition to the base 4.6.1 framework. 

Exchange 2013 CU13 contains the security fix for MS16-079- Security update for Microsoft Exchange

The Disk Reclaimer function in AutoReseed added support for Bitlocker.  The feature must be manually enabled. 

The Modern Public Folder migration issue  has been resolved

Outlook client remains disconnected after the mailbox is migrated to Exchange Server 2013 has been mitigated by reducing the Autodiscover AppPool database cache refresh interval  from 24 hours to 1 hour. 


Issues Resolved

This update also includes new daylight saving time (DST) updates for Exchange Server 2013. For more information about DST, go to Daylight Saving Time Help and Support Center.


Some Items For Consideration

As with previous CUs, CU13 follows the new servicing paradigm which was previously discussed on the blog.  The CU13 package can be used to perform a new installation, or to upgrade an existing Exchange Server 2013 installation to CU13.  You do not need to install Cumulative Update 4 or 5 for Exchange Server 2013 when you are installing CU13.  Cumulative Updates are well, cumulative.  What else can I say…

  • After you install this cumulative update package, you cannot uninstall the cumulative update package to revert to an earlier version of Exchange 2013. If you uninstall this cumulative update package, Exchange 2013 is removed from the server.

  • Place the server into maintenance mode prior to installing, confirm the install then take the server out of maintenance mode

  • Restart the server after installing the CU

  • Ensure that you consult with all 3rd party vendors which exist as part of your messaging environment.  This includes archive, backup, mobility and management services.

  • Ensure that you do not forget to install this update on management servers, jump servers/workstations and application servers where the management tools were installed for an application.  FIM and 3rd party user provisioning solutions are examples of the latter.

  • Ensure that the Windows PowerShell Script Execution Policy is set to “Unrestricted” on the server being upgraded or installed.  See KB981474

  • Disable file system antivirus prior to installing.

  • Once server has been restarted, re-enable file system antivirus.

  • Note that customised configuration files are overwritten on installation.  Make sure you have any changes fully documented!

  • While CU13 does not add any new AD Schema changes, if you are on an out-dated CU currently then deploying CU13 may contain AD Schema updates for your organisation – please test and plan accordingly!  Whether or not your AD Schema needs to be updated depends upon your initial Exchange 2013 version.  This will dictate if the AD Schema needs to be modified.  Check the values as noted in this post.

Please enjoy the update responsibly!

What do I mean by that?  Well, you need to ensure that you are fully informed about the caveats with the CU  and are aware of all of the changes that it will make within your environment.  Additionally you will need to test the CU your lab which is representative of your production environment.




Comments (19)
  1. James Auman says:

    Installed CU13 yesterday (was at CU12). Mid-day today inbound SMTP-based mail flow trickled to a halt. Rebooted the servers later in the day and it started up again. Any ideas what might have gone wrong?

    1. James Auman says:

      NOTE: I’ve installed CU 9, 10, 11 and 12 each time they were released. Never had this issue (or any others for that matter).

      1. Not seeing any other references on this issue at this time James. Will take a look around on this issue.

        Did the restart potentially apply a separate change that was waiting as a pending action?


  2. Paul Fisher says:

    According to the Exchange Server Supportability Matrix .net 4.6.1 is not compatible with Exchange 2013 CU13, it is only compatible with Exchange 2016 CU2.

    1. That should be updated to reflect this release. Ross has already commented on this.


    2. qayoum says:

      .Net 4.6.1 Support

      Support for .Net 4.6.1 is now available for Exchange Server 2016 and 2013 with these updates. We fully support customers upgrading servers running 4.5.2 to 4.6.1 without removing Exchange. We recommend that customers apply Exchange Server 2016 Cumulative Update 2 or Exchange Server 2013 Cumulative Update 13 before upgrading .Net FrameWork. Servers should be placed in maintenance mode during the upgrade as you would do when applying a Cumulative Update. Support for .Net 4.6.1 requires the following post release fixes for .Net as well.
      Windows Server 2008/2008R2 – KB3146716
      Windows Server 2012 – KB3146714
      Windows Server 2012R2 – KB3146715

      Ref :

      1. Indeed. And on this topic, .NET 4.6.2 is just release and should not be installed until testing and the support matrix has been updated.


  3. Mike says:

    We’ve just done a big jump to CU13 from plain old SP1, and all seemed good _except_ that the skipassource flag is now ignored on all the additional IPs. Don’t suppose anyone else has come across this? Our AD replication is currently broken as a result (d’oh!)
    Because it’s such a big jump I obviously can’t be sure that the problem’s in CU13 – nor can I think of a good reason why it would be – but google seems to be empty on the subject and it WAS working so just wondering if the reason it’s empty is because it’s so new. Hoping….(!)

    1. Mike says:

      Well, sort of ignores ‘skipassource’ –
      It respects the flag in the sense that it doesn’t register the additional IP address as additional A records for the server name.
      It just registers them as additional hosts for the domain root. Which is worse.

      Yes, this is also a DC (I know…), and it is only set to listen on one IP address in the Interfaces tab of the DNS manager.

      1. Hi Mike,

        I’d doubt this was directly related to CU13. Maybe the restart at the end applied a separate pending change?

        Been a while since I’ve used the skipassource since I have less need to create additional vDIRs in Exchange 2013, compared to Exchange 2010.


        1. Mike says:

          Yep – that’s also a possibility…

          Thank you for taking the time to reply!

          1. Mike says:

            Now sorted – and it really wasn’t anything to do with this. Nor is skipassource mis-behaving. It was an “unrelated” change on the server at the other end.

            1. Good deal 🙂


  4. Brian Hanson says:

    Since updating Exchange 2013 CU8 to CU13 both the ECP and the OWA fail to load after login; although the login knows if you enter an incorrect password.
    – The OWA returns HTTP 400 error.
    – The ECP returns: Server Error in ‘/ecp’ Application…
    – Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
    – Exception Details: System.IO.FileNotFoundException: Could not load file or assembly ‘Microsoft.Exchange.Common, Version=, Culture=neutral, PublicKeyToken=31bf3856ad364e35’ or one of its dependencies. The system cannot find the file specified.

    The Exchange server is running but of course I cannot run the ECP. Users are able to access e-mail externally using the Exchange App but not OWA.
    I’ve since discovered after searching through TechNet and other forums that there are several articles on this bug but no definitive resolution. All the suggestions either don’t work or require edits to objects in the ADSIEdit.msc that don’t exist. Apparently there is a newly released fix in CU14, but does that contain more bugs? Has anyone tried installing CU14 yet?
    Any resolutions would be much appreciated.

    1. Mathew says:

      If you come across ECP and OWA crashes after CU13 , please run updatecas.ps1 to update the CAS URLs . This will resolve the issue

      1. Eddie says:

        I got this error after CU13:
        Could not find a part of the path c:\program files\microsoft\exchange server\v15\frontend\httpproxy\owa\auth\15.0.1178\themes\resources\logon.css
        The updatecas.ps1 and updateconfig.ps1 scripts didn’t help either.
        Had to rename the folder in the path back to 15.0.1178, the CU13 changed it to 15.0.1210 (the CU13 build number which is correct).
        After renaming this folder the OWA and ECP sites worked immediately, even without reboot or IISReset.
        Where does Exchange get the value 15.0.1178? Does anyone know? It’s not in web.config and sharedweb.config, i checked it’s not there.

        1. Magudeeswaran M says:

          Installing Exchange 2013 CU13 has screwed up my infra, As Brian explained I also have experienced the same issue and nothing helped so far. Tried all these steps as explained by Eddie too, updatecas.ps1 and updateconfig.ps1 rename the folder back to 15.0.1178 nothing helped resolving the issue.

  5. Pradeep says:

    We applied CU13 this weekend. did not install .NET 4.6. Now when we login to EAC and go to groups we get error “your request couldn.t be completed. Please try again in a few minutes.”
    I can search individual group by name.

  6. Baldeo Rai says:

    Thank you for sharing this Article. Yesterday I did the up gradation from CU8 to CU13 but I got this error after CU13:
    Could not open the OWA page.
    Had copied the logon.aspx file from other mail server and placed it to c:\program files\microsoft\exchange server\v15\frontend\httpproxy\owa\auth\logon.aspx
    Post that able to view the OWA page but not abled to view the design page in OWA.
    Had copied the thems folder from other mail server at D:\Program Files\Microsoft\Exchange Server\V15\FrontEnd\HttpProxy\owa\auth\15.0.1076 and pated it at D:\Program Files\Microsoft\Exchange Server\V15\FrontEnd\HttpProxy\owa\auth\15.0.1210

    Restart the IIS and issue got resolved.

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