Unable to resume replication for database '{0}' due to a connection error. The Resume-MailboxDatabaseCopy cmdlet will attempt ...

Unable to resume replication for database '{0}' due to a connection error. The Resume-MailboxDatabaseCopy cmdlet will attempt to mark the database for Resume. Verify that the Microsoft Exchange Replication service is running and that the database copy has been resumed by using the Get-MailboxDatabaseCopyStatus cmdlet. Error: {1}.