<configSections>
    <section name="log4net" type="System.Configuration.IgnoreSectionHandler" />
  </configSections>
    
  <log4net>
    <appender name="LogFileAppender" type="log4net.Appender.FileAppender">
      <file value="../log.txt" />
      <layout type="log4net.Layout.PatternLayout">
        <footer value="[Footer]--Test By Ring1981 &#13;&#10;" />
        <conversionPattern value="%date [%thread] %-5level %logger [%ndc] &lt;%property{auth}&gt; - %message%newline" />
      </layout>
    </appender>

    <root>
      <appender-ref ref="LogFileAppender" />
    </root>
  </log4net>

    public class Program
    {
        
        static void Main(string[] args)
        {
            LogTest a = new LogTest();
            a.TestMethod();

            Console.ReadLine();
        }

    }
    public class LogCOM 
    {
        public static readonly ILog log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
    }

    public class LogTest 
    {
        public string TestMethod()
        {
            try
            {
                List<string> list = new List<string>();
                list.Add("a");
                list.Add("b");
                list.Add("c");
                list.Add("d");
                string e = list.FirstOrDefault(x => x == "e");

                e.ToString();

                return "tet";
            }
            catch (Exception ex)
            {
                LogCOM.log.Error("test",ex);
                return "";
            }
        }
    }

[assembly: log4net.Config.XmlConfigurator(Watch = true)]