customErrors mode="On" defaultRedirect="404.aspx">
error statusCode="403" redirect="404.aspx" />
error statusCode="404" redirect="404.aspx" />
error statusCode="400" redirect="404.aspx" />
/customErrors>

protected void Application_Error(object sender, EventArgs e)
{
//在出現未處理的錯誤時運行的代碼
this.FileNotFound_Error();
}
/// summary>
/// 404錯誤處理
/// /summary>
private void FileNotFound_Error()
{
HttpException erroy = Server.GetLastError() as HttpException;
if (erroy != null erroy.GetHttpCode() == 404)
{
Server.ClearError();
string path = "~/404.aspx";
Server.Transfer(path);
//Context.Handler = PageParser.GetCompiledPageInstance(path, Server.MapPath(path), Context);
}
}