Mongo log4net appender sample using nuget package log4mongo-net

app.config

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

  <connectionStrings>
    <add name="mongolog" connectionString="{mymongoconnectionstring}"/>
  </connectionStrings>
  <appSettings>
    <add key="log4net.Internal.Debug" value="true"/>
  </appSettings>

  <log4net>

    <appender name="MongoDBAppender" type="Log4Mongo.MongoDBAppender, Log4Mongo">
      <!-- 
    MongoDB database connection in the format:
    mongodb://[username:password@]host1[:port1][,host2[:port2],...[,hostN[:portN]]][/[database][?options]]
    See http://www.mongodb.org/display/DOCS/Connections for connectionstring options 
    If no database specified, default to "log4net"
    -->
      <!--<connectionString value="mongodb://localhost" />-->
      <!-- 
    Name of connectionString defined in web/app.config connectionStrings group, the format is the same as connectionString value.
    Optional, If not provided will use connectionString value
    -->
      <connectionStringName value="mongolog" />
      <!-- 
    Name of the collection in database
    Optional, Defaults to "logs"
    -->
      <collectionName value="console_test" />

      <field>
        <name value="timestamp" />
        <layout type="log4net.Layout.RawTimeStampLayout" />
      </field>
      <field>
        <name value="level" />
        <layout type="log4net.Layout.PatternLayout" value="%level" />
      </field>
      <field>
        <name value="thread" />
        <layout type="log4net.Layout.PatternLayout" value="%thread" />
      </field>
      <field>
        <name value="logger" />
        <layout type="log4net.Layout.PatternLayout" value="%logger" />
      </field>
      <field>
        <name value="message" />
        <layout type="log4net.Layout.PatternLayout" value="%message" />
      </field>
      <field>
        <name value="mycustomproperty" />
        <layout type="log4net.Layout.RawPropertyLayout">
          <key value="mycustomproperty" />
        </layout>
      </field>
    </appender>

    <root>
      <level value="INFO" />
      <appender-ref ref="MongoDBAppender" />
    </root>

  </log4net>
  <startup>
    <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5.1" />
  </startup>
</configuration>

program.cs

using log4net;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

[assembly: log4net.Config.XmlConfigurator()]

namespace ConsoleApplication1
{
    class Program
    {
        static ILog log = LogManager.GetLogger(typeof(Program));

        static void Main(string[] args)
        {
            log.Info("TEST INFO");

            log.Fatal("TEST FATAL");

        }
    }
}

Hello,I have a problem. If collection exist in my mongodb, I catch error.
But If collection isn't exist in my mongodb , Insert log .
I sharing my error detail . I wait your help @krcourville

:ERROR [MongoDBAppender] ErrorCode: GenericFailure. Failed in DoAppend
System.AggregateException: One or more errors occurred. ---> System.FormatException: The GuidRepresentation for the reader is CSharpLegacy, which requires the binary sub type to be UuidLegacy, not UuidStandard.