将项目从 .NET5 转换为 .NET Framework 4.8

Question

Long story, summarized... I started working on a solution creating many projects (like class libraries) for the solution. Then I ended up needing to use a third-party SDK for something I had an expensive license for. Come to find out, that third-party SDK only supported .NET Framework .

Because my solution was based in .NET 5/Core and the SDK in .NET Framework I had a big issue. They can not exist in the same environment and reference each other. So, on to biting the bullet and spending hours converting all my projects to .NET Framework 4.8 while singing a neverending song of curse words...

The Issue

My first class library I'm trying to convert from .NET5 to .NET 4.8 happens to have a Nuget package installed. That Nuget is Newtonsoft.Json Version="12.0.3" ( https://www.nuget.org/packages/Newtonsoft.Json ).

After changing the framework in the project file, VSCode is telling me the Newtonsoft namespace can not be found. This makes me think that the Nuget I have installed is not compatible with .NET Framework 4.8.

Answer 1

The issue I was running into was the namespace Newtonsoft could not be found after changing the framework from net5.0 to net48 .

The issue was OmniSharp that was giving a false positive. I restarted VSCode and the issue went away once VSCode loaded with the new framework being used.

Answer 2

.NET supports cross platform targeting which means you can have your SDK style .NET5 project multi-targets both net5 and net48 . In future, if the third-party library targets .NET Core then you can simply change the TargetFrameworks property.

A similar issue has been discussed here https://github.com/dotnet/runtime/discussions/40304 incase if that helps.