Impact of Changing Framework Order in runtime.config.json on Application Stability

Question

Description:

I am working on a .NET 8 WPF application that undergoes obfuscation using SmartAssembly. During the build, runtime.config.json is generated automatically, but SmartAssembly picks WindowsBase.dll from Microsoft.NETCore.App instead of Microsoft.WindowsDesktop.App, causing obfuscation errors. i.e. During obfuscation with SmartAssembly, WindowsBase.dll was being resolved from Microsoft.NETCore.App instead of Microsoft.WindowsDesktop.App, leading to an invalid symbol error.

To resolve this, I modified the framework order in runtime.config.json to ensure Microsoft.WindowsDesktop.App is listed before Microsoft.NETCore.App. This change resolved the obfuscation issue, but I want to confirm:

1. Is it safe to modify runtime.config.json manually post-build via a script?
2. Can this impact runtime behavior on client machines, especially in framework-dependent deployments?
3. Is there an official way to enforce framework resolution order during build instead of modifying runtime.config.json manually?

Any official guidance on this would be highly appreciated.

Environment:

• .NET 8.0

WPF Application

SmartAssembly Obfuscation

Windows 10/11 Deployment

Thanks!

Answer 1

Hi, @Subhabrata Sahoo. Welcome to Microsoft Q&A. 

Is it safe to manually modify [appname].Runtime.config.json after building?

If you modify the configuration in [appname].Runtime.config.json, the runtime will read this file when the application is loaded. If the format or content of the file does not meet the requirements, the runtime may fail to load or throw an exception. In addition, when your application depends on a specific [appname].Runtime.config.json configuration, these settings will affect the runtime deployed to the client computer. If the runtime version of the client computer is incompatible with the configuration file, the application may not start.

However, if you only adjust the order of framework loading, it generally does not affect the operation of the application, as long as the versions and compatibility of all framework dependencies are correct.

However, projects need to be updated frequently over time, and manual modifications every time are not conducive to maintenance.

Set [appname].Runtime.config.json during the build.

Add a .json file with the contents of your target's [appname].Runtime.config.json. For example: add runtimeconfig.json and add the following code.

{
    "runtimeOptions": {
      "frameworks": [
        {
          "name": "Microsoft.WindowsDesktop.App",
          "version": "8.0.0"
        },
        {
          "name": "Microsoft.NETCore.App",
          "version": "8.0.0"
        }
      ]
    },
    "configProperties": {
      "System.Runtime.Serialization.EnableUnsafeBinaryFormatterSerialization": true,
      "CSWINRT_USE_WINDOWS_UI_XAML_PROJECTIONS": false
    }
}

Add <Target> code in <Project> of .csproj to replace the contents of [appname].Runtime.config.json with the contents of .json before build.

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>WinExe</OutputType>
    <TargetFramework>net8.0-windows</TargetFramework>
    <Nullable>enable</Nullable>
    <ImplicitUsings>enable</ImplicitUsings>
    <UseWPF>true</UseWPF>
  </PropertyGroup>

	<Target Name="CopyRuntimeConfig" BeforeTargets="Build">
		<Copy SourceFiles="runtimeconfig.json" DestinationFiles="$(OutDir)[appname].runtimeconfig.json" />
	</Target>

</Project>

Replace [appname] with the name of your project.

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