'NU1202: Package is not compatible with netcoreapp2.0 (.NETCoreApp,Version=v3.0)

I have created a new Solution where I have added a few projects. They are either ASP.NET Core, Class Libraries or NUnit Test projects. Both the ASP.NET and test projects experience the same errors, where I cannot add packages to the projects. The error I get is NU1202, a few examples:

Error   NU1202  Package Newtonsoft.Json 10.0.1 is not compatible with netcoreapp3.0 (.NETCoreApp,Version=v3.0). 
Package Newtonsoft.Json 10.0.1 does not support any target frameworks.  

Error   NU1202  Package System.AppContext 4.1.0 is not compatible with netcoreapp3.0 (.NETCoreApp,Version=v3.0). 
Package System.AppContext 4.1.0 supports:
  - monoandroid10 (MonoAndroid,Version=v1.0)
  - monotouch10 (MonoTouch,Version=v1.0)
  - netstandard (.NETStandard,Version=v0.0)
  - xamarinios10 (Xamarin.iOS,Version=v1.0)
  - xamarinmac20 (Xamarin.Mac,Version=v2.0)
  - xamarintvos10 (Xamarin.TVOS,Version=v1.0)
  - xamarinwatchos10 (Xamarin.WatchOS,Version=v1.0)

These errors comes after I've tried to add Swashbuckle.AspNetCore to my ASP.NET project.

I have tried to clear the caches, checked that the NuGet version is up to date (it is 5.3). I don't know what else I can do. Any suggestions?

Edit: I have tried downgrading, even to netcoreapp2.0. But this does not solve the problem

To be clear, I have only added Swashbuckle.AspNetCore, not Newtonsoft.Json or or System.AppContext, however that is still the error messages i get

c++sharpasp.netnuget-package-restore


Solution 1:[1]

You have two options:

  1. Use Swashbuckle.AspNetCore

or

  1. Downgrade your project from .NET Core 3.0

Option 1: Use Swashbuckle.AspNetCore

Since you're using a .NET Core 3.0 project, you can use the Swashbuckle NuGet Package that is specifically designed for .NET Core, Swashbuckle.AspNetCore.

Option 2: Downgrade Project

You'll need to downgrade your project from .NET Core 3.0 to .NET Core 2.2.

In the csproj file, change the TargetFramework version from netcoreapp3.0 to netcoreapp2.2.

Here's an example csproj file that uses .NET Core 2.2:

<Project Sdk="Microsoft.NET.Sdk.Web">
    <PropertyGroup>
        <TargetFramework>netcoreapp2.2</TargetFramework>
    </PropertyGroup>
</Project>

Solution 2:[2]

If you are installing from NuGet Packages, choose the latest stable version from the version dropdown and then install. It worked for me:)

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution Source
Solution 1
Solution 2 RISHU GUPTA

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