How to log exceptions

Exceptions require special treatment in NLog. You need to call method on the Logger class which takes Exception as its second argument. The method name matches the log level:

• TraceException()
• DebugException()
• InfoException()
• WarnException()
• ErrorException()
• FatalException()
• LogException() – takes log level as a parameter

You typically call one of these methods in the catch handler:

try 
{ 
    // some code which may throw 
} 
catch (MyException ex) 
{ 
    logger.ErrorException("Got exception.", ex); 
}

To write the details of the exception, use the ${exception} layout renderer in your layout. Depending on the desired output you may want to specify different value for the “format” argument. The following example displays the result of calling ToString() on the exception object.

<nlog> 
  <targets> 
    <target name="f" type="File" 
            layout="${longdate} ${message} ${exception:format=tostring}"/> 
  </targets> 
  <rules> 
    <logger name="*" writeTo="f"/> 
  </rules> 
</nlog>