Upgrading to this new release is critical for continued support of add-ins to be installed in Microsoft Outlook in Microsoft Exchange Server 2013. All new add-in manifest files will be signed by using a new RFC3161-based timestamping. This will deprecate the use of SHA1-based timestamping. You will not be able to install or start any new office add-ins until you upgrade to this new version.
How to get this update
To get this update, install the following updates:
Learn about the terminology that Microsoft uses to describe software updates.