log4net:ERROR ConfigureFromXml called with null 'element' parameter - asp.net-core

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>

Answer 2

In fact, the accepted response is not accurate, the problem with the XML is the .NET configuration on top of log4net configuration. The original configuration file is a .NET configuration file instead of a log4net one, and it's rooted with a configuration node instead of with a log4net node.
The second configuration XML on the other hand is correct, but it's replacing the original configuration (maybe with a better one, for sure), not only fixing the problem but replacing the original configuration with a new one.
The a better response for the change would be:
Remove the configuration root node from the original xml file together with the configSections node and leave the log4net node as root of the XML resulting in:
<?xml version="1.0" encoding="utf-8" ?>
<!-- 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>
Reconfigure your appender with a Rolling appender if needed...