Checking File Extension
string ext = System.IO.Path.GetExtension(FileUpload1.FileName); if (ext != ".jpg" && ext != ".jpeg") { Response.Write("accept only jpg file"); } else { FileUpload1.SaveAs(Server.MapPath("~") + "//upload//" + FileUpload1.FileName); Image1.ImageUrl = "~/upload/" + FileUpload1.FileName; }