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the merge process could not query the last sent and received generations

Error messages:
The merge process could not query the last sent and received generations. (Source: MSSQL_REPL, Error number: MSSQL_REPL-2147200929)
Get help: http://help/MSSQL_REPL-2147200929

SQL Server Network Interfaces: Error Locating Server/Instance Specified [xFFFFFFFF].  (Source: MSSQLServer, Error number: -1)
Get help: http://help/-1

A network-related or instance-specific error has occurred while establishing a connection to SQL Server. Server is not found or not accessible. Check if instance name is correct and if SQL Server is configured to allow remote connections. For more information see SQL Server Books Online. (Source: MSSQLServer, Error number: -1)
Get help: http://help/-1

Login timeout expired (Source: MSSQLServer, Error number: 0)
Get help: http://help/0

The merge process failed to execute a query because the query timed out. If this failure continues, increase the query timeout for the process. When troubleshooting, restart the synchronization with verbose history logging and specify an output file to which to write. (Source: MSSQLServer, Error number: 0)
Get help: http://help/0

Issue:

In SQL Replication Monitor is the following message.
 

The merge process could not query the last sent and received generations. (Source: MSSQL_REPL, Error number: MSSQL_REPL-2147200929)

Causes:

The Merge Agent on the Subscriber needs to be restarted.

Solution:

Log in to SQL Server Management Studio and connect to the Subscriber.

Under SQL Server Agent>Jobs, locate the database subscription that shows the above message.
Right click it and select "Stop Job".

Then, expand Replication>Local subscriptions, find the database, right click it.
From the context menu, select View Synchronization Status.


In the synchronization status screen select the 'Start' button