.NET Core - Using system.diagnostics in App.config

Question

I'm migrating a console app from .NET Legacy to .NET Core 2.2. In that app, I'm using the HttpClient and HttpRequestMessage classes. Sometimes, requests made with these classes fail. For that reason, I had a system.diagnostics block in my App.config file to log the raw request for diagnosing issues. While this worked in my legacy app, I now get an error in .NET Core.

When I start my app, I see the following error:

ConfigurationErrorsException: Unrecognized configuration section system.diagnostics.

The only thing I've added to my App.config file is: <system.diagnostics></system.diagnostics>, which is an empty config block. If I remove that block, my app runs as expected.

How do I add the system.diagnostics configuration used in my legacy app into my .NET Core app so I can trace the raw web requests again?

Thanks!

Are you sure that your application doesn't have a system.diagnostics block inside of the 'configuration' block already? If so you can't instantiate two blocks in the same project. — Dr. Roggia
@Dr.Roggia How would I know? I have a single App.config file. It's pretty empty. Does .NET core automatically inject some configuration details for console apps that I'm not aware of? — Some User
@CodeCaster The SO question uses the XML config approach, which is what I'm using and want. However, the answer is for ASP.NET and uses the .json config syntax. I'm not using ASP.NET, I'm building a console app. I want to use the XML config approach and not the .json approach. — Some User

vSzemkel vSzemkel · Accepted Answer · 2020-09-01T09:45:37

The thing is that .NET Core doesn't pre-register config section for system.diagnostics.

Try to emplace this at the beginning of App.config, just under <configuration> line:

<configSections>
    <section name="system.diagnostics" type="System.Diagnostics.DiagnosticsConfigurationHandler"/>
</configSections>

.NET Core - Using system.diagnostics in App.config

1 Answers