Symptoms
When you use a MERGE statement to sync tables on an instance of SQL Server 2012, 2014, or 2016 that has change data capture enabled, the sync operation is unsuccessful. Additionally, you may receive an error message that resembles the following:
Cannot insert duplicate key row in object object_name with unique index index_name.
The duplicate key value is (duplicate_key_value).
Resolution
Update information
This issue is fixed in the following cumulative updates of SQL Server:
Each new cumulative update for SQL Server contains all the hotfixes and all the security fixes that were included with the previous cumulative update. Check out the latest cumulative updates for SQL Server:
Status
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
References
Learn about the terminology that Microsoft uses to describe software updates.
