log4net:ERROR ConfigureFromXml called with null 'element' parameter

Question

We are using log4net library with .NET Core for writing logs in file. But we are getting this error when executing the application "log4net:ERROR ConfigureFromXml called with null 'element' parameter". Here is our Program.cs file:

public class Program
{
    public static void Main(string[] args)
    {
        XmlDocument log4netConfig = new XmlDocument();
        log4netConfig.Load(File.OpenRead("log4net.config"));
        var repo = log4net.LogManager.CreateRepository(Assembly.GetEntryAssembly(), typeof(log4net.Repository.Hierarchy.Hierarchy));
        log4net.Config.XmlConfigurator.Configure(repo, log4netConfig["log4net"]);

        BuildWebHost(args).Run();
    }

    public static IWebHost BuildWebHost(string[] args) =>
        WebHost.CreateDefaultBuilder(args)
            .UseStartup<Startup>()
            .Build();
}

Here is Configure method in Startup.cs file:

public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
    {
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }
        loggerFactory.AddConsole(LogLevel.Trace);
        loggerFactory.AddLog4Net();

        app.UseIdentityServer();
    }

Here is log4net.config file:

    <?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <configSections>
    <section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler,log4net, Version=1.2.10.0, Culture=neutral, PublicKeyToken=1b44e1d426115821" />
  </configSections>

  <!-- Log4net Logging Setup -->
  <log4net>
    <appender name="FileAppender" type="log4net.Appender.FileAppender,log4net">
      <file value="c:\LogFiles\Applications\IdentityServer\log.txt" />
      <appendToFile value="true" />
      <lockingModel type="log4net.Appender.FileAppender+MinimalLock" />
      <layout type="log4net.Layout.PatternLayout">
        <conversionPattern value="%date [%thread] %level %logger - %message%newline" />
      </layout>
      <filter type="log4net.Filter.LevelRangeFilter">
        <levelMin value="INFO" />
        <levelMax value="FATAL" />
      </filter>
    </appender>

    <root>
      <level value="DEBUG"/>
      <appender-ref ref="FileAppender"/>
    </root>
  </log4net>
</configuration>

Answer 1

Replace your log4net.config with below code :

    <?xml version="1.0" encoding="utf-8" ?>
<log4net>
  <appender name="RollingLogFileAppender" type="log4net.Appender.RollingFileAppender">
    <lockingModel type="log4net.Appender.FileAppender+MinimalLock"/>
    <file value="C:\Temp\" />
    <datePattern value="yyyy-MM-dd.'txt'"/>
    <staticLogFileName value="false"/>
    <appendToFile value="true"/>
    <rollingStyle value="Date"/>
    <maxSizeRollBackups value="100"/>
    <maximumFileSize value="15MB"/>
    <layout type="log4net.Layout.PatternLayout">
      <conversionPattern value="%date [%thread] %-5level App  %newline %message %newline %newline"/>
    </layout>
  </appender>
  <root>
    <level value="ALL"/>
    <appender-ref ref="RollingLogFileAppender"/>
  </root>
</log4net>