How to get the Stack trace when logging exceptions with NLog?

Question

When I use the default layout with NLog it only prints the name of the exception. I've been told that the log4jxmlevent layout doesn't prints nothing about the exception. What layout will help me?

Example code:

try
{
    throw new SystemException();
}
catch (Exception ex)
{
    logger.Error("oi", ex);
}

Default layout output:

2011-01-14 09:14:48.0343|ERROR|ConsoleApplication.Program|oi

log4jxmlevent output:

<log4j:event logger="ConsoleApplication.Program"
           level="ERROR"
           timestamp="1295003776872"
           thread="9">
<log4j:message>oi</log4j:message>
<log4j:NDC />
<log4j:locationInfo class="ConsoleApplication.Program"
                    method="Void Main(System.String[])"
                    file="C:\Users\User\Documents\Visual Studio 2010\Projects\ConsoleApplication\ConsoleApplication\Program.cs"
                    line="21" />
<nlog:eventSequenceNumber>3</nlog:eventSequenceNumber>
<nlog:locationInfo assembly="ConsoleApplication, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null" />
<log4j:properties>
  <log4j:data name="log4japp"
              value="true" />
  <log4j:data name="log4jmachinename"
              value="MACHINE" />
</log4j:properties>

Rolf Kristensen · Accepted Answer · 2023-08-17 15:06:50Z

111

As documented in How to Log Exceptions, starting with NLog 4.0, pass the exception as the first parameter to Error, for example like this:

logger.Error(ex, "ex");

and a custom layout

layout="${exception:format=ToString}${newline}"

edited Aug 17, 2023 at 15:06

Rolf Kristensen

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answered Jan 14, 2011 at 12:31

Jader Dias

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7 Comments

Shane Over a year ago

Is this in addition to an existing layout?

Clay Over a year ago

FYI, this approach is deprecated. github.com/NLog/NLog/wiki/How-to-Log-Exceptions

Julian Over a year ago

Explaining the comment of @Clay: The logging line is now changed to logger.Error("Got exception.", ex); but the 'custom layout' is fine

Ilya Serbis Over a year ago

Note that usage of both ToString and StackTrace cause stacktrace duplication in log output. ${exception:format=ToString} would be enough

Jess Over a year ago

@JaderDias this answer is very confusing. Can you please correct the answer or flag the comments for delete (as obsolete).

|

Rolf Kristensen · Accepted Answer · 2021-12-19 13:55:23Z

25

Use the overloads that take an Exception as the second argument:

catch(Exception crap)
{
    log.Error(crap, "Something went horribly wrong.");
}

Then in your layout include the ${exception} layout renderer:

<target ...
    layout="${longdate} ${message} ${exception:format=ToString}" />

Sources:

edited Dec 19, 2021 at 13:55

Rolf Kristensen

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answered Dec 31, 2014 at 22:03

Clay

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Comments

Edward Brey · Accepted Answer · 2015-07-01 15:46:20Z

22

As documented in How to Log Exceptions, starting with NLog 4.0, pass the exception as the first parameter to Error, for example like this:

logger.Error(ex, "Nickers!");

In the NLog configuration (e.g. in web.config or app.config), include ${exception:format=tostring} in the layout, for example like this:

<target name="f" type="File" layout="${longdate} ${message} ${exception:format=tostring}"/>

answered Jul 1, 2015 at 15:46

Edward Brey

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1 Comment

mcdon Over a year ago

Can use Conditional Formatting in the layout for exceptions. The following is close to the default layout

<target name="f" type="File" layout="${longdate}|${level:uppercase=true}|${message}${onexception:${newline}${exception:format=tostring}}"/>

.

Michael Armitage · Accepted Answer · 2019-01-09 09:44:04Z

12

As of NLog 4.5 you can now use:

logger.Error(exception, message);

and layout as follows:

"${longdate} ${level} ${message} ${exception:format=@}"

The @ means serialize all Exception-properties into Json-format

answered Jan 9, 2019 at 9:44

Michael Armitage

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1 Comment

Ryan Gaudion Over a year ago

This is the answer I was looking for - gets full Json version of the Exception in the logs rather than just Exception type and message

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