Write Exception log on catch portion in asp.net C#

////////  Call exp log

protected void Page_Load(object sender, EventArgs e)

    {

        try

        {

        }

        catch (Exception ex)

        {

            WriteErrorLog(ex);

        }

    }

/////////// Write log

public static void WriteErrorLog(Exception ex)

    {

        var line = Environment.NewLine + Environment.NewLine;

        string ErrorlineNo = ex.StackTrace.Substring(ex.StackTrace.Length - 7, 7),

                  Errormsg = ex.GetType().Name.ToString(),

                   extType = ex.GetType().ToString(),

                    expUrl = HttpContext.Current.Request.Url.ToString(),

                    hostIp = "",

             ErrorLocation = ex.Message.ToString();

        if (HttpContext.Current.Request.UserHostAddress != null)

        {

            Int64 macip = new Int64();

            string macSrc = macip.ToString("X");

            if (macSrc == "0")

            {

                if (Convert.ToString(HttpContext.Current.Request.UserHostAddress) != "127.0.0.1")

                {

                    hostIp = Convert.ToString(HttpContext.Current.Request.UserHostAddress);

                }

            }

        }

        try

        {

            string filepath = HttpContext.Current.Server.MapPath("~/ExceptionDetailsFile/");  //Text File Path

            if (!Directory.Exists(filepath))

            {

                Directory.CreateDirectory(filepath);

            }

            filepath = filepath + DateTime.Today.ToString("dd-MM-yy") + ".txt";   //Text File Name

            if (!File.Exists(filepath))

            {

                File.Create(filepath).Dispose();

            }

            using (StreamWriter sw = File.AppendText(filepath))

            {

                string error = 

"Log Written DateTime :" + " " + DateTime.Now.ToString() + Convert.ToString(line) + 

"Error Line No. :" + " " + ErrorlineNo + Convert.ToString(line) + 

"Error Message :" + " " + Errormsg + Convert.ToString(line) + 

"Exception Type :" + " " + extType + Convert.ToString(line) + 

"Error Location :" + " " + ErrorLocation + Convert.ToString(line) + 

"Error Page Url :" + " " + expUrl + Convert.ToString(line) + 

"User Host IP :" + " " + hostIp + Convert.ToString(line);

                sw.WriteLine("----Exception On " + " " + DateTime.Now.ToString() + "----");

                sw.WriteLine("------------------------------------------------------------");

                sw.WriteLine(Convert.ToString(line));

                sw.WriteLine(Convert.ToString(error));

                sw.WriteLine("-------------*End*-------------");

                sw.WriteLine(Convert.ToString(line));

                sw.Flush();

                sw.Close();

            }

        }

        catch (Exception e)

        {

            e.ToString();

        }

    }