Restrict the size of file upload in asp.net

I want to restrict my file size upload to a certain limit. But, the problem here is that I want to provide a popup alert when the upload size is exceeded . But , instead the web page here shows the following error ``` HTTP Error 404.13 - Not Found ``` `The request filtering module is configured to deny a request that exceeds the request content length.` Here's my code ``` protected void Button1_Click(object sender, EventArgs e) { if (fuDocpath.HasFiles) { try { DateTime now = DateTime.Now; lbldateStamp.Text = now.ToString("mm_dd_yyyy_hh_mm_ss"); //string foldername = lblsessionID.Text + "_" + lbldateStamp.Text; string folderpath = (Server.MapPath("~/Uploaded_Files/") + lblsessionID.Text + "_" + lbldateStamp.Text + "/"); Directory.CreateDirectory(folderpath); if (fuDocpath.PostedFile.ContentLength < 20970000) { try { foreach (HttpPostedFile files in fuDocpath.PostedFiles) { string filename = Path.GetFileName(files.FileName); string folderpath1 = folderpath + "/"; fuDocpath.SaveAs(folderpath1 + filename); lblName.Text = lblName.Text + "|" + filename; lblerror.Text = string.Empty; } } catch (Exception eex) { ClientScript.RegisterStartupScript(this.GetType(), "myalert", "alert('" + eex.Message + "')", true); } } } catch (Exception ex) { lblerror.Text = "File couldn't be uploaded." + ex.Message; lblName.Text = string.Empty; } } } ```