NLog internal log not working with ASP.Net MVC

Question

I have a problem with NLog for logging its internal logs with this configuration

<?xml version="1.0" encoding="utf-8" ?>
<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  throwExceptions="true"
  internalLogFile="${basedir}/App_Data/NLog.log"
  internalLogLevel="Trace">

   <targets>
      <target name="debug"
              xsi:type="File" 
              fileName="${basedir}/App_Data/Site.log" />
   </targets>

   <rules>
      <logger name="*"
              writeTo="debug" />
   </rules>
</nlog>

The target "debug" is working well, but the internalLogFile is only working if I set it for exemple to "D:/NLog.log".

Any idea why this happening?

Answer 1

You can't use layout renderers ${...} in the internalLogFile property. They are for a target's layout only:

<target layout="${...}" />

Try to use relative path like "..\App_Data\NLog.log"

Update NLog 4.6 enables some simple layouts.

Answer 2

The internalLogFile attribute needs to be set to an absolute path and the executing assembly needs to have permission to write to that absolute path.

The following worked for me.

1. Create a folder somewhere - e.g. the route of your c: drive, e.g. c:\logs
2. Edit the permissions of this folder and give full control to everyone
3. Set your nlog config: internalLogFile="C:\logs\nlog.txt"

Remember to clean up after yourself and not leave a directory with those sorts of permissions on