Assume that you're in a Microsoft Exchange Server 2013 and Exchange Server 2016 coexistence environment. When an Exchange Server 2016 user tries to access a calendar that's shared from an Exchange Server 2013 user, an error message may occur and the calendar can't be displayed.
This issue occurs because Exchange Server 2013 can't understand the calendar access request that's sent from Exchange Server 2016.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
Learn about the terminology that Microsoft uses to describe software updates.