Why do I keep getting "It is invalid to show a modal dialog or form when the application is not running in UserInteractive mode...."
when I try to use a common dialog on my web application and how do I fix this?

You cannot create and show an Open File dialog from your web application. Remember that a web application has no state; the request is sent from the client browser to the web server. The web server builds the web page and sends it to the client browser and the request is complete and there is no connection between the client and server.

Why are you trying to display a Open File dialog in your web form? There may be viable alternatives to what you are trying to accomplish.

Thearon

I, too, have been looking at trying to provide a way for users to see folders/files on the server. Maybe the answer is to simply permit them the use of FTP?

I too was looking at providing a dialog for opening folders on the server.
Perhaps the answer is found in using FTP?

If you want users to download files, then perhaps you should use server side code to build a web page that displays the file names with links to the files. This would probably be the best way to do this.

Thearon

I had the same problem, to get around it you have to thread the OpenFileDialog:

Here is the thread instance
-----------
OpenFileDialog_Class oOpenDialog = new OpenFileDialog_Class();
Thread tFileNameThread = new Thread(new ThreadStart(oOpenDialog.StartThread));
tFileNameThread.SetApartmentState(ApartmentState.S TA); //This must be set
tFileNameThread.Start(); //Start the thread
tFileNameThread.Join();
sTemplate = oInvoice.GetTemplateName(); //Get the path/name of the file to use
---------------
Below is the class for the thread above

using System;
using System.IO;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Windows.Forms;

/// <summary>
/// Summary description for OpenFileDialog_Class
/// </summary>
public class OpenFileDialog_Class
{
    public string sTemplate = null;
    public OpenFileDialog_Class()
    {
        //
        // TODO: Add constructor logic here
        //
        //GetTemplate();
    }
    public void StartThread()
    {
        sTemplate = GetTemplate();
    }

    [STAThread] //Must have this declared, or your thread crashes
    public string GetTemplate()
    {
        string sTemplate = null;
        try
        {
            OpenFileDialog openFileDialog = new OpenFileDialog();
            openFileDialog.InitialDirectory = Directory.GetCurrentDirectory();
            openFileDialog.Filter = "Word Template (*.dot)|*.dot|All files (*.*)|*.*";
            openFileDialog.FilterIndex = 1;
            openFileDialog.RestoreDirectory = true;

            if (openFileDialog.ShowDialog() == DialogResult.OK)
            {
                int iStartFile = openFileDialog.FileName.LastIndexOf("\\");
                try
                {
                    sTemplate = openFileDialog.FileName;
                }
                catch (Exception ex)
                {
                    System.Console.WriteLine(ex.Message);
                }
            }
        }
        catch (Exception ex)
        {
            //LogWriter_Class sw = new LogWriter_Class();
            //sw.logError(ex, " error, check the log file.", " Error");
        }
        return sTemplate;
    }
    [STAThread]
    public string GetTemplateName()
    {
        return sTemplate;
    }
}

This works ok, only problem is the OpenFileDialog is not in Focus, your IE is, but you can Alt+Tab it easy enough.

My use is to select a Word Template document to create an Invoice for my sales.

Hope this helps.
Scott Thornton
www.thornton-imports.com

Cannot use these

using System.Windows.Forms;
using System.Web.UI.WebControls.WebParts;

In web forms

any other work around, so we can have OpenFileDialog or SaveFileDialog in a webform?

no