Logging with filters stopped working after upgrade to NLog 5

Question

I'm using Nlog for years to ... log details and exceptions from an application.

The NLog.config file is unchanged for years and it looks as below

<nlog>

<targets>       
    <target xsi:type="File" name="f"
       fileName="${basedir}/logs/${shortdate}.log" 
       layout="${longdate}|${level:uppercase=true}|${logger}|${message}${onexception:inner=${newline}${exception:format=tostring}}" />
        
    <target xsi:type="File" name="fe"
       fileName="${basedir}/logs/${shortdate}_err.log"
       layout="${longdate}|${level:uppercase=true}|${logger}|${message}${onexception:inner=${newline}${exception:format=tostring}}" />
</targets>

<rules>
    <logger name="*" minlevel="Trace" maxlevel="Warn" writeTo="f" >
       <filters>
          <when condition="contains('${message}','[HTTPS]')" action="Ignore"/>
          <when condition="contains('${message}','[EmailCachingHelper]')" action="Ignore"/>
       </filters>
   </logger>
       
   <logger name="*" minlevel="Error" writeTo="fe" ></logger>
</rules>

</nlog>

The problem is, since a while, about two weeks ago, the f log file is no longer created. The exceptions log file, fe, *_err.log is still created ok.

In that date I updated Nlog from 4.7.15 to 5.0.0

Does anyone know what could cause this? Is there any additional config setting I need to do?

Thank you

Answer 1

After some research I found a breaking change in config from 4.x to 5.x

The LoggingRule Filters DefaultAction was changed from Neutral to Ignore.

This means NO output, if using dynamic filters and not already using defaulAction="Ignore".

The fix was to add DefaultAction to Log

<filters defaultAction="Log">

which fixed the problem