title: Log4net error with XmlHierarchyConfigurator. Missing Filter Property
body: <p>One of our WebApis stopped outputting logs recently. In the Trace file we were getting this message:</p>
  
  <p>log4net:ERROR XmlHierarchyConfigurator: Cannot find Property [filter] to set object on [log4net.Repository.Hierarchy.Hierarchy]</p>
  
  <p>The config file looks as below and I'm assuming the filter in the error is the same filter in the config so I'm not sure why it can't find it. 
  I upgraded to the latest version of log4net and that solved the issue for a few days and then we got the "Cannot find Property [filter]" error again. The config file hasn't changed at all over this period.</p>
  
  <pre><code>&lt;configuration&gt;
    &lt;configSections&gt;
      &lt;section name="log4net"
          type="log4net.Config.Log4NetConfigurationSectionHandler, log4net" /&gt;
    &lt;/configSections&gt;
    &lt;log4net&gt;
      &lt;root&gt;
        &lt;level value="ALL" /&gt;
        &lt;appender-ref ref="RollingFileAppender"/&gt;
      &lt;/root&gt;
      &lt;filter type="log4net.Filter.LevelMatchFilter"&gt;
        &lt;acceptOnMatch value="true" /&gt; &lt;!--change to false to exclude info logs --&gt;
        &lt;levelToMatch  value="INFO" /&gt;
      &lt;/filter&gt;
      &lt;appender name="RollingFileAppender" type="log4net.Appender.RollingFileAppender"&gt;
        &lt;file value="Logs/Log.txt" /&gt;
        &lt;appendToFile value="true" /&gt;
        &lt;rollingStyle value="Size" /&gt;
        &lt;maxSizeRollBackups value="10" /&gt;
        &lt;maximumFileSize value="1001KB" /&gt;
        &lt;staticLogFileName value="true" /&gt;
        &lt;layout type="log4net.Layout.PatternLayout"&gt;
          &lt;conversionPattern value="%date [%thread] %-5level: %message%newline" /&gt;
        &lt;/layout&gt;
      &lt;/appender&gt;
    &lt;/log4net&gt;
  
  &lt;/configuration&gt;
  </code></pre>
  
  <p>It's weird that it worked for a while, stopped, updgraded, worked for a while, stopped. I'm at at loss as to what could have changed to make it stop working either time.</p>
  
  <p>Thanks in advance for any help.</p>