<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<log4net>
<root>
<level value="ALL" />
<appender-ref ref="console" />
<appender-ref ref="file" />
</root>
<appender name="console" type="log4net.Appender.ColoredConsoleAppender">
<mapping>
<level value="ERROR" />
<foreColor value="Red, HighIntensity" />
</mapping>
<mapping>
<level value="INFO"/>
<foreColor value="Green,HighIntensity"/>
</mapping>
<mapping>
<level value="Debug"/>
<foreColor value="Yellow,HighIntensity"/>
</mapping>
<mapping>
<level value="Warn"/>
<foreColor value="Purple,HighIntensity"/>
</mapping>
<mapping>
<level value="Fatal"/>
<foreColor value="Cyan,HighIntensity"/>
</mapping>
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%date %level %logger - %message%newline" />
</layout>
</appender>
<appender name="file" type="log4net.Appender.RollingFileAppender">
<file value="myapp.log" />
<appendToFile value="true" />
<rollingStyle value="Size" />
<maxSizeRollBackups value="5" />
<maximumFileSize value="10MB" />
<staticLogFileName value="true" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%date [%thread] %level %logger - %message%newline" />
</layout>
</appender>
</log4net>
</configuration>

 private static readonly log4net.ILog logger = log4net.LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType);
        static void Main(string[] args)
        {
            Log4netDemo();
            Console.ReadLine();
        }

        static void Log4netDemo()
        {           
            logger.Info($"{DateTime.Now.ToString("yyyyMMddHHmmssffff")}");            
            logger.Error($"{DateTime.Now.ToString("yyyyMMddHHmmssffff")}");
            logger.Debug($"{DateTime.Now.ToString("yyyyMMddHHmmssffff")}");
            logger.Fatal($"{DateTime.Now.ToString("yyyyMMddHHmmssffff")}");
            logger.Warn($"{DateTime.Now.ToString("yyyyMMddHHmmssffff")}");             
        }

<appender name="file" type="log4net.Appender.RollingFileAppender">     
      <file type="log4net.Util.PatternString" value="Logs\\Common\\%date{yyyy-MM-dd-HH-mm-ss-ffff}.log" />
      <appendToFile value="true" />
      <rollingStyle value="Size" />
      <maxSizeRollBackups value="5" />
      <maximumFileSize value="10MB" />
      <staticLogFileName value="true" />
      <layout type="log4net.Layout.PatternLayout">
        <conversionPattern value="%date [%thread] %level %logger - %message%newline" />
      </layout>
    </appender>