Package X is not compatible with netcoreapp3.1

Question

I'm trying to run my .net core 3.1 project in VS 2019 but I'm getting errors like a below during building.

Severity Code Description Project File Line Suppression State Error NU1202 Package System.Diagnostics.DiagnosticSource 4.5.0 is not compatible with netcoreapp3.1 (.NETCoreApp,Version=v3.1).Package System.Diagnostics.DiagnosticSource 4.5.0 does not support any target frameworks. WebApi.Base C:\Users\ilyas.varol.TEST\source\repos\performancemanagementprojects\WebApi.Base\WebApi.Base.csproj

Notes:

• I made reinstalling all packages and .net core 3.1 sdk
• The same project is running in another computer

UPDATE

I still haven't solve my problem. Therefore I want to elaborate my question with screenshots. I hope someone can help me.

Error list

Nuget Package Manager > Consolidate

Answer 1

First, clean nuget caches or delete all files under C:\Users\xxx(current user)\.nuget\packages .

Then, delete bin and obj folder.

Rebuild the project to test again.

Answer 2

I clicked right click on sln and then I clicked "Clean Solution" and Rebuild Solution". Finally, My problem is solved.

Answer 3

Following worked for me on VS 2019,

Tools-->Nuget Package Manager-->Package Manager Settings-->General-->Clear All NuGet Cache(s)

Answer 4

I had the same problem, as mentioned in the docs I updated the target framework .

Specifically, of my class libraries (in Blazor server core 3.1).

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFramework>netcoreapp3.1</TargetFramework> //remove this
    <TargetFramework>net6.0</TargetFramework>        //add this
  </PropertyGroup>

</Project>

After this, you need to remove the bin , obj folder and rebuild the project.

This should get you are up and running again.

Answer 5

For me 5.0.10 worked properly. Today the latest version of this NuGet package is 6.0.6 but I tried 5.0.10 and worked properly