Project 'ClassLibrary1.csproj' targets 'netstandard2.1'. It cannot be referenced by a project that targets '.NETFramework,Version=v4.8'
According to the compatibility matrix, my NetFramework 4.8 project should not be able to reference libraries up to NetStandard 2. So the @Henk Holterman answer is true.
The versions listed here represent the rules that NuGet uses to determine whether a given .NET Standard library is applicable.
.NET Framework will not support .NET Standard 2.1 or any other later version. For more details, see this blog post.
What can I do?
- If your library doesn't need the very latest features, use .net standard 2.0
in general, a library should aim to support the lowest possible version.
or
- port your WPF app to .NET Core 3 (preview)
Update:
.Net Core 3 has been released and you can also use the stable version of it.