How do I try trap fileUpload(Ajax Toolkit) exception?

[Ronald Ray]

I am using FileUpload(Ajax Toolkit) within my application.
I have placed a try-catch around the function call to initiate the file upload. When I try to upload any file greater than 4 megabytes, the application crashes and does not propagate the exception to my application.

How can I trap this exception?

 
protected void UploadFile_Click(object sender, EventArgs e)
    {
 
        //Initialize
        lError.Text = "";
        lInfo.Text = "";
 
        bool IsActive = true;
        string ExtType;
        string UserName = (string)Session["UserName"];
 
        try
        {
 
            if (FileUploadPDF.HasFile == false)
            {
                // No file uploaded!
                lError.Text = "You have not selected a file to upload.";
 
            }
            else
            {
                int FileSize = FileUploadPDF.PostedFile.ContentLength;
                string FileName = FileUploadPDF.FileName;
                ExtType = FileName.Substring(FileName.Length - 3, 3).ToLower();
 
                if (FileSize > 4069000)
                {
                    lError.Text = "Your file was not uploaded because it exceeds the 4 MB size limit.";
                    return;
                }
                if ((ExtType != "pdf") & (ExtType != "txt"))
                {
                    lError.Text = "This application only accepts pdf and txt files";
                    return;
                }
                if (VehicleMaintenanceID == 0)
                {
                    lError.Text = "A maintenance record must exist before you can attach a document";
                    return;
                }
 
                MaintSummary ms = new MaintSummary();
 
                int result = ms.UploadDocuments(FileName,
                                                IsActive,
                                                FileUploadPDF.FileBytes,
                                                ExtType,
                                                VehicleMaintenanceID,
                                                UserName);
 
                if (result == 0)
                {
                    // Display the uploaded file's details
                    lInfo.Text = string.Format(
                            @"Successfully Uploaded file: {0}<br />
                            File size (in bytes): {1:N0}<br />
                            Content-type: {2}",
                            FileUploadPDF.FileName,
                            FileUploadPDF.FileBytes.Length,
                            FileUploadPDF.PostedFile.ContentType);
 
                }
                else
                {
                    lError.Text = "Uploading document failed";
                }
 
            }
 
        } // end of try
        catch (System.Exception ex)
        {
            lError.Text = ex.Message;
        }
 
    }
 

[mzmishra]

It's a config issue. The reason you can't hook in is because IIS doesn't even send the request to your app when the file size is too large. Try one of the following:

You can modify your machine or web config maxRequestLength value for the application

[ZiadElmalki]

You will get an unhandled httpexception that you can catch from an httpmodule or from your global.asax. I worked on a weird app where we caught the error in the global.asax, displayed an alert, and then redirected them back to the page they came from.

[lcddr]

When a file exceeds upload limit, the application isn't notified. You must handle the response on client. See:
http://it.expertmonster.com/question...eptio-114.html