Use the below simple code. public void CreateFolder(string url, string foldername,string documentlibname) { try { ClientContext clientContext = new ClientContext(url); Web web = clientContext.Web; var query = clientContext.LoadQuery(web.Lists.Where(p => p.Title == documentlibname));## Heading ## clientContext.ExecuteQuery(); List list = query.FirstOrDefault(); var folder = list.RootFolder; clientContext.Load(folder); clientContext.ExecuteQuery(); string[] PathElements = foldername.Split(new char[] { '/' }, StringSplitOptions.RemoveEmptyEntries); for (int i = 0; i < PathElements.Length; i++) { folder = folder.Folders.Add(PathElements[i].ToString()); clientContext.ExecuteQuery(); }

 //folder = folder.Folders.Add(foldername); //clientContext.ExecuteQuery(); } catch (System.Exception ex) { throw; } } 

Use the below simple code.

 public void CreateFolder(string url, string foldername,string documentlibname) { try { ClientContext clientContext = new ClientContext(url); Web web = clientContext.Web; var query = clientContext.LoadQuery(web.Lists.Where(p => p.Title == documentlibname));## Heading ## clientContext.ExecuteQuery(); List list = query.FirstOrDefault(); var folder = list.RootFolder; clientContext.Load(folder); clientContext.ExecuteQuery(); string[] PathElements = foldername.Split(new char[] { '/' }, StringSplitOptions.RemoveEmptyEntries); for (int i = 0; i < PathElements.Length; i++) { folder = folder.Folders.Add(PathElements[i].ToString()); clientContext.ExecuteQuery(); }  //folder = folder.Folders.Add(foldername); //clientContext.ExecuteQuery(); } catch (System.Exception ex) { throw; } }