. net core throws an error and writes it Txt file

        #region  write file   If the file exists, add it one by one , If it doesn't exist, create a new one 
        /// <summary>
        ///  write file 
        /// </summary>
        /// <param name="Path"> File path </param>
        /// <param name="content"> The contents of the document </param>
        // Invoke the sample 
        //string webRootPath = _hostingEnvironment.WebRootPath;  // Get relative path 
        //string strUploadPath = webRootPath + "/Document/";
        //string fileLogName = " Error log " + DateTime.Now.ToLongDateString() + "Log.txt";
        //WriteFile(strUploadPath + fileLogName, " Test content ");
        public static void WriteFile(string path, string content)
        {
            if (!System.IO.File.Exists(path))
            {
                System.IO.FileStream f = System.IO.File.Create(path);
                f.Close();
            }
            System.IO.StreamWriter f2 = new System.IO.StreamWriter(path, true, System.Text.Encoding.GetEncoding("gb2312"));
            f2.WriteLine(content);
            f2.Close();
            f2.Dispose();
        }
        #endregion