Why do some C# applications have an app.config file and others do not?

Question

Why do some C# applications have an app.config file and others do not? Both of these solutions were initialized as Visual C# Windows Form Application's.

Answer 1

Hello @William Thompson,

Welcome to Microsoft Q&A forum.

The first screenshot shows that it’s a .NET based project, and the second screenshot shows that it’s a .NET Framework based project.

As you can see, by default, the App.config file exists in .NET Framework based projects, but not in .NET based projects.

Start from .NET 5/6, .NET based projects use an appsettings.json file(you may need to add it into your project if you want to configure it) to replace an app.config file.

Here’s the related document and more detailed information: App.config

.NET Framework uses the App.config file to load settings for your app, such as connection strings and log provider configuration. Modern .NET uses the appsettings.json file for app settings.

If you don’t want to use the appsettings.json file, you can add the System.Configuration.ConfigurationManager NuGet package to your app and your code will compile and use the App.config file.

Happy coding.

Best Regards,

Tianyu

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