Microsoft has released Cumulative Update 3 for Exchange Server 2013.

From the Microsoft Exchange Team blog:

We would like to call attention to an important fix in Exchange Server 2013 Cumulative Update 3 which impacts customers who rely upon Backup and Recovery mechanisms to protect Exchange data. Cumulative Update 3 includes a fix for an issue which may randomly prevent a backup dataset taken from Exchange Server 2013 from restoring correctly. Customers who rely on Backup and Recovery in their day-to-day operations are encouraged to deploy Cumulative Update 3 and initiate backups of their data to ensure that data contained in backups may be restored correctly. More information on this fix is available in KB2888315.

In addition to the customer reported fixes in Cumulative Update 3, the following new enhancements and improvements to existing functionality have also been added for Exchange Server 2013 customers:

  • Usability improvements when adding members to new and existing groups in the Exchange Administration Console
  • Online RMS available for use by non-cloud based Exchange deployments
  • Improved admin audit log experience
  • Windows 8.1/IE11 no longer require the use of OWA Light

More information on these topics can be found in our What’s New in Exchange Server 2013Release Notes and product documentation available on TechNet.

Cumulative Update 3 includes Exchange related updates to Active Directory schema and configuration. For information on extending schema and configuring the active directory please review the appropriate TechNet documentation. Also, to prevent installation issues you should ensure that the Windows PowerShell Script Execution Policy is set to “Unrestricted” on the server being upgraded or installed. To verify the policy settings, run the Get-ExecutionPolicy cmdlet from PowerShell on the machine being upgraded. If the policies are NOT set to Unrestricted you should use the resolution steps in KB981474 to adjust the settings.

Cumulative Update 3 is available for download here.

For deployment steps refer to this guide to installing cumulative updates for Exchange Server 2013.

About the Author

Paul Cunningham

Paul is a former Microsoft MVP for Office Apps and Services. He works as a consultant, writer, and trainer specializing in Office 365 and Exchange Server. Paul no longer writes for


  1. Dan Kregor

    I’m curious, what are the implications of downgrading from CU3 to CU2? I have a customer who uses MobileIron, which at present doesn’t support CU3 (not officially anyway). Whilst I haven’t tested MobileIron against CU3, the customer would prefer to have everything “above board” just in case they require vendor support.

    Your thoughts?!

    1. Avatar photo
      Paul Cunningham

      A downgrade is effectively an uninstall and then reinstall of the server. You can’t uninstall a CU the way you could with Exchange 2010 URs for example, because the CU is a full build-to-build upgrade.

      There could be implications for example with DAG members where the database schema has been updated to a later level than what you’re trying to “downgrade” servers to.

      For MobileIron to lag behind CU releases on support sounds like a frustrating situation.

  2. Greg

    I just deployed RTM. Can CU3 be installed on RTM without the need to CU1 or CU2?

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