Cumulative Update 21 for Microsoft Exchange Server 2013 was released on June 19, 2018. This cumulative update includes fixes for nonsecurity issues and all previously released fixes for security and nonsecurity issues. These fixes will also be included in later cumulative updates for Exchange Server 2013.
This update also includes new daylight saving time (DST) updates for Exchange Server 2013. For more information about DST, see Daylight Saving Time Help and Support Center.
Issues that this cumulative update fixes
This cumulative update fixes the issues that are described in the following Microsoft Knowledge Base articles:
- 4133605 Cmdlets to create or modify a remote shared mailbox in an on-premises Exchange environment
- 4133604 User can't log on to a POP/IMAP account by using NTLM authentication in Exchange Server 2013
- 4133618 Unexpected error occurs when running the Get-DatabaseAvailabilityGroupNetwork cmdlet in Exchange Server 2013
- 4133620 “HTTP 500 due to ADReferralException” when a user tries to view detail properties of mailboxes in a child domain in Exchange Server
- 4058473 An Office 365 primary mailbox user cannot be assigned full access permissions for an on-premises mailbox in Exchange Server
- 4094167 The MSExchangeRPC service crashes with a System.NullReferenceException exception in Exchange Server 2013
- 4095974 “System.InvalidOperationException” occurs when the "Enable-MailPublicFolder" cmdlet is run against a public folder in Exchange Server
- 4092041 Description of the security update for Microsoft Exchange Server 2013 and 2016: May 8, 2018
- 4294205 POP3 services intermittently stop in an Exchange Server 2013 environment
- 4294204 Changing "IsOutOfService" to "False" in an earlier Exchange Server version does not immediately update in a later Exchange Server environment
Get Cumulative Update 21 for Exchange Server 2013
- Download Cumulative Update 21 for Exchange Server 2013 (KB4099855) now.
- Download Exchange Server 2013 CU21 UM Language Packs now.
- The Cumulative Update 21 package can be used to run a new installation of Exchange Server 2013 or to upgrade an existing Exchange Server 2013 installation to Cumulative Update 21.
- You do not have to install any previously released Exchange Server 2013 cumulative updates or service packs that were released before Cumulative Update 21 before you install Cumulative Update 21.
Cumulative update information
This cumulative update requires Microsoft .NET Framework 4.7.1.
A component that's used within Exchange requires a new Visual C++ prerequisite to be installed with Exchange Server. The prerequisite can be downloaded at Visual C++ Redistributable Packages for Visual Studio 2013. For more information, see KB 4295081.
The setup process for Exchange Server 2013 identifies any missing prerequisites. For more information about the prerequisites for the setup of Exchange Server 2013, see Exchange 2013 prerequisites.
You may have to restart the computer after you apply this cumulative update package.
You do not have to make any changes to the registry after you apply this cumulative update package.
After you install this cumulative update package, you can't uninstall the package to revert to an earlier version of Exchange Server 2013. If you uninstall this cumulative update package, Exchange Server 2013 is removed from the server.
For more information about the coexistence of Exchange Server 2013 and earlier versions of Exchange Server in the same environment, see Exchange 2013 System Requirements.
For more information about other Exchange updates, see Exchange Server Updates: Build numbers and release dates.