I've asked a question about exception layout renderer at SO

However seems that writing custom layout renderer is not so complex So here i will keep IndentExceptionLayoutRenderer.cs source code

This renderer allows to show exception using readable format (from my point of view) in the log (file or console). Additionally it does not log full exception stack trace if it is logged second time (it happens if exception is rethrown like inner exception).

src\NLog.config is a sample configuration that shows how layout can be parameterized for console and file logging

Below you can find IndentException class properties that can help you to adjust exception logging

property name	description
Indent	what character(s) are placed before exception in the log (default is tab)
StackTraceIndent	indent between each stack trace line (default is two tab characters)
BeforeType	is written before exception type name (default [)
AfterType	is written after exception type name (default ])
Separator	separator between exception type and message
LogStack	to log stack trace or not (for console logger e.g.)

how it works

The package does not contain any assemlby just a source file.

This is IndentExceptionLayoutRenderer.cs text file. It has IndentExceptionLayoutRenderer class defined within YourNamespace.NLog.Extention namespace.

All .cs files are copied to text template .pp when package is released and nupkg file is created. Namespace YourNamespace is changed to the current project default namespace value.

Then .pp files are injected into every project that references IndentException package.

how to use

Sample folder contains sample project how package may be consumed.

• Add package to a project
• create/adjust nuget.config file and add extensions element referencing your project assembly name

	<extensions>
		<add assembly="YOUR_PROJECT_ASSEMBLY_NAME"/>
	</extensions>

Initialize NLog as usually and get exception formatting extention working.

console log sample

Here is console output for layout like layout="${level} ${message}${onexception:${newline}${IndentException:LogStack=false:separator=	:beforeType=:aftertype=}}" there is no stack trace shown (because of LogStack=false)

Error tryException failure
        ArgumentException       outer exception
        KeyNotFoundException    innerException
Error failed to start NLogTest
        ArgumentException       bad try
        ArgumentException       outer exception
        KeyNotFoundException    innerException

file log sample

Below you can find file logging sample using layout layout="[${threadid}] ${longdate} ${level} (${logger}) ${message}${onexception:${newline}${IndentException}}

outer exception and inner exception stack trace is logged only once. Error type and message are logged only if error processing code tries to log the same exception second time

[1] 2019-01-27 19:56:57.7258 Debug (YourNamespace.NLog.Extention.Test.Program) starting
[1] 2019-01-27 19:56:57.7769 Error (YourNamespace.NLog.Extention.Test.Classes.UnitOfWork) tryException failure
	[ArgumentException] outer exception
		at YourNamespace.NLog.Extention.Test.Classes.UnitOfWork.outerException()
		at YourNamespace.NLog.Extention.Test.Classes.UnitOfWork.tryException()
	[KeyNotFoundException] innerException
		at YourNamespace.NLog.Extention.Test.Classes.UnitOfWork.innerException()
		at YourNamespace.NLog.Extention.Test.Classes.UnitOfWork.outerException()
[1] 2019-01-27 19:56:57.7769 Error (YourNamespace.NLog.Extention.Test.Program) failed to start NLogTest
	[ArgumentException] bad try
		at YourNamespace.NLog.Extention.Test.Classes.UnitOfWork.tryException()
		at YourNamespace.NLog.Extention.Test.Program.Main(String[] args)
	[ArgumentException] outer exception
	[KeyNotFoundException] innerException
[1] 2019-01-27 19:56:57.8344 Debug (YourNamespace.NLog.Extention.Test.Program) the end