У вашего броузера проблема в совместимости с HTML5
End-to-end walk-through of porting a .NET Framework WPF app to .NET Core 3.
The code sample can be found at https://github.com/dotnet/windows-desktop/tree/master/Samples/BeanTrader. The initial project state is in the NetFx directory and the final, migrated .NET Core project, is in the NetCore directory.
Resources:
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Intro to .NET Core 3: https://docs.microsoft.com/en-us/dotnet/core/whats-new/dotnet-core-3-0
.NET Core 3 Migration Guidance: https://github.com/dotnet/samples/tree/master/wpf
Microsoft.Windows.Compatibility package: https://www.nuget.org/packages/Microsoft.Windows.Compatibility
Compat Analyzers: https://github.com/dotnet/platform-compat