Exporting sharepoint list items to excel by csom c# [duplicate]

"The property or field has not been initialized. It has not been requested or the request has not been executed. It may need to be explicitly requested."

This error means you will need to load listItems collection before accessing it, here is a csom code demo to export list item into csv file for your reference:

 static void Main(string[] args)
        {
            string csvFilePath = @"c:\temp\myCSV.csv";
            StringBuilder items = new StringBuilder();
            ClientContext clientContext = new ClientContext("http://sp/sites/dev/");
            List list = clientContext.Web.Lists.GetByTitle("CustomList");
            CamlQuery caml = new CamlQuery();
            ListItemCollection listItems = list.GetItems(caml);
            clientContext.Load(list);
            clientContext.Load(listItems);
            clientContext.ExecuteQuery();
            foreach (ListItem listItem in listItems)
            {
                items.Append(listItem.Id + ",");
                items.Append(listItem.FieldValues["Name"]);
                items.AppendLine();
            }
            System.IO.File.WriteAllText(csvFilePath, items.ToString());
        }