I have seen post for this error but no solution, so I am posting again in hopes of getting an answer. I am trying to send a record to a Salesforce to Salesforce connection if it meets certain parameters. However, received the error posted in the subject line. Below is the code that I am trying to execute:

trigger SimpleCaseTrigger on Case (after update) {
    // Define connection id 
    Id networkId = ConnectionHelper.getConnectionId('Connection Name'); 
    List <Case> sendToConn = New List<Case>();
    List<PartnerNetworkRecordConnection> prncList = new List<PartnerNetworkRecordConnection>();
    for (Case c : Trigger.New){
        //Test to that the case has been successfully closed and has not been sent to Connection Before
        if (c.ConnectionReceivedId == null && c.ConnectionSentID == null && c.Status == 'Successfully Closed'){
            sendToConn.add(c);
            System.debug('Case #'+ c.CaseNumber + ' added.');
        }
    }
    
    //Create Connection to send to Connection
    for (Case newCases : sendToConn){
        PartnerNetworkRecordConnection newConnection =
                    new PartnerNetworkRecordConnection(
                        ConnectionId = networkId,
                        LocalRecordId = newCases.Id,
                        SendClosedTasks = false,
                        SendOpenTasks = false,
                        SendEmails = false,
                        ParentRecordId = newCases.AccountId);
        prncList.add(newConnection);
    }
    database.insert(prncList);
    
}