System.Text.Json 10.x dependency breaks .NET Native toolchain compatibility #937

Version

v6.5.7

Platform

UWP (Universal Windows Platform) with .NET Native Toolchain enabled (<UseDotNetNativeToolchain>true</UseDotNetNativeToolchain>)

Steps to reproduce

Steps to reproduce

1. Create a new project using the "Blank App (Universal Windows) (.NET Native)" template.
   (Note: Do not use the standard "Blank App (Universal Windows)" template if it uses Modern .NET/Native AOT, as the issue is specific to the legacy .NET Native toolchain).
2. Install YoutubeExplode version 6.5.7.
3. Ensure the project is configured to use the .NET Native Toolchain.
   • In Visual Studio: Project Properties > Build > "Compile with .NET Native toolchain".
   • Or in .csproj: ensure <UseDotNetNativeToolchain>true</UseDotNetNativeToolchain> is set (this is default for Release builds).
4. Build the project in Release.
5. Observed Result: The build fails with MCG0007 errors due to System.Text.Json 10.x.

Details

The recent update bumped the System.Text.Json polyfill for netstandard2.0 targets to version 10.0.2.

In the YoutubeExplode.csproj, the current logic is:

<PackageReference
  Include="System.Text.Json"
  Version="10.0.2"
  Condition="!$([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', 'netcoreapp3.0'))"
/>

Since UWP targets netstandard2.0 (and is NOT compatible with netcoreapp3.0), this condition evaluates to true, forcing the project to download and link System.Text.Json v10.x.

The Issue:
The .NET Native toolchain (MCG) used by UWP is stricter than modern Native AOT. The v10.x branch of System.Text.Json has drifted from the compatibility baseline required by the legacy .NET Native compiler. This causes compilation errors and runtime marshalling exceptions because the v10 binaries contain references (or trigger paths in dependencies) that the static compiler cannot resolve or deems unsafe for the AppContainer.

Proposed Solution

I suggest pinning the System.Text.Json reference to the 9.x (LTS) branch specifically for netstandard2.0 targets, as this is the intersection point for UWP and older Native AOT toolchains.

You can achieve this in two ways:

Option A: Simple Downgrade
Since netstandard2.0 is the primary legacy target in this project, simply reverting the version in the existing condition is the cleanest fix.

<PackageReference
  Include="System.Text.Json"
  Version="9.0.2"
  Condition="!$([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', 'netcoreapp3.0'))"
/>

Option B: Granular Configuration (If you want to keep v10 for .NET Framework)
If you prefer to keep System.Text.Json v10.x for other potential legacy targets (like .NET Framework 4.8), you can split the reference to target netstandard2.0 explicitly:

<PackageReference
  Include="System.Text.Json"
  Version="9.0.2"
  Condition="'$(TargetFramework)' == 'netstandard2.0'"
/>

<PackageReference
  Include="System.Text.Json"
  Version="10.0.2"
  Condition="'$(TargetFramework)' != 'netstandard2.0' And !$([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', 'netcoreapp3.0'))"
/>

By applying either of these changes, UWP consumers will be able to compile with the .NET Native toolchain again without breaking modern .NET consumers.

Checklist

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• I have provided a descriptive title for this issue
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• I have not read any of the above and just checked all the boxes to submit the issue