Writing logs to file

Question

I have some troubles while writing logs from log4net to the file. I seem to do all as described in manual, but that does not work. Here is my logging.config file:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <configSections>
    <section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler, log4net" />
  </configSections>
  <log4net>
    <appender name="FileAppender" type="log4net.Appender.FileAppender">
      <file value="log.txt" />
      <appendToFile value="true" />
      <lockingModel type="log4net.Appender.FileAppender+MinimalLock" />
      <layout type="log4net.Layout.PatternLayout">
        <conversionPattern value="%date [%thread] %-5level %message%newline" />
      </layout>
    </appender>
  </log4net>
</configuration>

Please help with an example of configuration file which actually works.

Answer 1

Here is a complete step-by-step guide to adding Log4Net to your project, under Visual Studio 2012 and .NET 4.5.

1. Add a new C# console app to your solution.

2. Select Tools >> Library Package Manager >> Manage NuGet Packages For Solution and search for log4net. Install it, and select which project(s) you want to add the log4net references.

3. Edit Program.cs:

using System;
namespace Log4Net
{    
    class Program
    {
        private static readonly log4net.ILog log = log4net.LogManager.GetLogger
                (System.Reflection.MethodBase.GetCurrentMethod().DeclaringType);
        static void Main(string[] args)
        {
            Console.WriteLine("Writing to \"log.txt\" in the same directory as the .exe file.\n");
            log.Info("Info logging");
            try
            {
                throw new Exception("Exception!");
            }
            catch (Exception e)
            {
                log.Error("This is my error", e);
            }
            Console.WriteLine("[any key to exit]");
            Console.ReadKey();
            }
        }
    }
}

4. Add log4.config, right click and select Properties then select Copy to Output Directory - Copy If Newer.

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <configSections>
    <section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler, log4net" />
  </configSections>

  <log4net>
    <appender name="RollingFileAppender" type="log4net.Appender.RollingFileAppender">
      <file value="log.txt" />
      <appendToFile value="true" />
      <rollingStyle value="Size" />
      <maxSizeRollBackups value="10" />
      <maximumFileSize value="250KB" />
      <staticLogFileName value="true" />
      <layout type="log4net.Layout.PatternLayout">
        <conversionPattern value="%date [%thread] %-5level %logger [%property{NDC}] - %message%newline" />
      </layout>
    </appender>
    <root>
      <level value="ALL" />
      <appender-ref ref="RollingFileAppender" />
    </root>
  </log4net>
</configuration>

5. Edit App.Config so it matches the following:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <startup> 
        <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5" />
    </startup>
    <appSettings>
        <add key="log4net.Config" value="log4.config"/>
        <add key="log4net.Config.Watch" value="True"/>
        <add key="log4net.Internal.Debug" value="False"/>
    </appSettings>
</configuration>

6. Run the program and observe the file log.txt that is created in the output \bin\Debug\ directory:

   2013-08-10 11:54:26,798 [10] INFO  Log4Net.Program [(null)] - Info logging
   2013-08-10 11:54:26,824 [10] ERROR Log4Net.Program [(null)] - This is my error
   System.Exception: Exception!
      at Log4Net.Program.Main(String[] args) in C:\Test\Log4Net\Program.cs:line 14
   

7. In the future, if you want to add log4net to another Project, select Tools >> Library Package Manager >> Manage NuGet Packages For Solution select log4net and click Manage then tick the Projects you want to add log4net to.

Answer 2

You don't seem to have a <root> element that references your appender:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <configSections>
    <section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler, log4net" />
  </configSections>

    <log4net>
      <appender name="RollingFileAppender" type="log4net.Appender.RollingFileAppender">
        <file value="log.txt" />
        <appendToFile value="true" />
        <rollingStyle value="Size" />
        <maxSizeRollBackups value="10" />
        <maximumFileSize value="250KB" />
        <staticLogFileName value="true" />
        <layout type="log4net.Layout.PatternLayout">
          <conversionPattern value="%date [%thread] %-5level %logger [%property{NDC}] - %message%newline" />
        </layout>
      </appender>
      <root>
        <level value="INFO" />
        <appender-ref ref="RollingFileAppender" />
      </root>
    </log4net>
</configuration>

Answer 3

Did you call the configure method when the application starts for the first time ?

log4net.Config.XmlConfigurator.Configure();

If yes. You should be good. Check the file permissions on the disk you are writing.

If you want you can enable log4net internal debugging also to figure out what is wrong.

http://logging.apache.org/log4net/release/faq.html#troubleshooting