Sharepoint - Creating Nested Folders via Client Object Model

Try not calling clientContext.Load, for example this works for me:

var folder = list.RootFolder;
clientContext.Load(folder);
clientContext.ExecuteQuery();
folder = folder.Folders.Add("Folder 1");
folder.Folders.Add("Folder 2");
clientContext.ExecuteQuery();

How to create Folder (including nested) via CSOM in SharePoint

/// <summary>
/// Create Folder (including nested) client object
/// </summary>
/// <param name="web"></param>
/// <param name="listTitle"></param>
/// <param name="fullFolderPath"></param>
/// <returns></returns>
public static Folder CreateFolder(Web web, string listTitle, string fullFolderPath)
{
    if (string.IsNullOrEmpty(fullFolderPath))
        throw new ArgumentNullException("fullFolderPath");
    var list = web.Lists.GetByTitle(listTitle);
    return CreateFolderInternal(web, list.RootFolder, fullFolderPath);
}


private static Folder CreateFolderInternal(Web web, Folder parentFolder, string fullFolderPath)
{
    var folderUrls = fullFolderPath.Split(new char[] { '/' }, StringSplitOptions.RemoveEmptyEntries);
    string folderUrl = folderUrls[0];
    var curFolder = parentFolder.Folders.Add(folderUrl);
    web.Context.Load(curFolder);
    web.Context.ExecuteQuery();

    if (folderUrls.Length > 1)
    {
        var folderPath = string.Join("/", folderUrls, 1, folderUrls.Length - 1);
        return CreateFolderInternal(web, curFolder, folderPath);
    }
    return curFolder;
}

Usage

 using (var ctx = new ClientContext("https://contoso.intranet.com/"))
 {
       var folder = CreateFolder(ctx.Web, "Shared Documents", "FolderA/SubFolderA/SubSubFolderA");
 }

How about something like this:

 public static Folder EnsureFolder(ClientContext ctx, Folder ParentFolder, string FolderPath)
    {
        //Split up the incoming path so we have the first element as the a new sub-folder name 
        //and add it to ParentFolder folders collection
        string[] PathElements = FolderPath.Split(new char[] { '/' }, StringSplitOptions.RemoveEmptyEntries);           
        string Head = PathElements[0];
        Folder NewFolder = ParentFolder.Folders.Add(Head);
        ctx.Load(NewFolder);
        ctx.ExecuteQuery();

        //If we have subfolders to create then the length of PathElements will be greater than 1
        if (PathElements.Length > 1)
        {
            //If we have more nested folders to create then reassemble the folder path using what we have left i.e. the tail
            string Tail = string.Empty;
            for (int i = 1; i < PathElements.Length; i++)
                Tail = Tail + "/" + PathElements[i];

            //Then make a recursive call to create the next subfolder
            return EnsureFolder(ctx, NewFolder, Tail);
        }
        else
            //This ensures that the folder at the end of the chain gets returned
            return NewFolder;            
    }

and then you can call it with following:

ctx.Load(TargetList.RootFolder);
ctx.ExecuteQuery();
Folder NewFolder = EnsureFolder(ctx, TargetList.RootFolder, "/Folder1/Folder2/Folder3");