Exchange 2016 CU2 Released

Exchange 2016 CU2 has been released to the Microsoft download centre!  Exchange 2016 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 2016 and can be used to install a fresh server or to update a previously installed one. Exchange 2013 has the same servicing methodology.

Exchange 2016 CU2 Download

This is build 15.01.0466.034 of Exchange 2016 and the update is helpfully named ExchangeServer2016-x64-CU2.iso which allows us to easily identify the update.  Details for the release are contained in KB 3135742.

Exchange 2016 CU2 contains AD Schema changes.  


Updates Of Particular Note

Exchange 2016 CU2 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 2016 CU2 contains the security fix for MS16-079- Security update for Microsoft Exchange

As previously announced: DAG Activation Preference Behavior Change in Exchange Server 2016 CU2

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

Get-ExchangeServer cmdlet has been updated in Exchange Server 2016 CU2 to reflect the Exchange 2016 ServerRole definitions; Mailbox or Edge.  The IsClientAccessServer property of the ExchangeServer object can be used in scripts where it is looking for a role definition of ClientAccess. 

The Exchange self signed certificate is now SHA2 based.  But remember, friends don’t let friends use self signed certs….


Issues Resolved



Some Items For Consideration

Exchange 2016 follows the same servicing paradigm for Exchange 2013 which was previously discussed on the blog.  The CU package can be used to perform a new installation, or to upgrade an existing Exchange Server 2016 installation to this CU.  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 2016. If you uninstall this cumulative update package, Exchange 2016 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!

  • CU2 contains AD Schema updates for your organisation – please test and plan accordingly! 

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.



Rhoderick Milne [MSFT]

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