Symptoms
Assume that you have a Microsoft Exchange Server 2013 database availability group (DAG) in a co-existing environment that has Exchange Server 2013 and Server 2016 deployed. When you run the Add-DatabaseAvailabilityGroup cmdlet from Exchange Server 2013 to add an Exchange Server 2016 Mailbox server as a member of the DAG (and vice versa), the operation is successful.
Cause
This is a known issue in Exchange Server 2013 for DAG member server version checking.
Resolution
To fix this issue, install Cumulative Update 11 or a later cumulative update for Exchange Server 2013.
Status
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
