检测到 NuGet 包的版本冲突

Question

I am working on an ASP.Net core 2.1 web app project. I have 1 project in my solution and 3 other libraries, it's and advanced architecture (data access layer ( DAL ), business layer ( BL ), common layer ( CL )), so i need to add references to connect some libraries and project. I have added CL reference to my project and to libraries DAL and BL . Now I have to add reference BL to my project, but when I add I get this type of error:

Version conflict detected fr Microsoft.EntityFrameworkCore/ Install/reference Microsoft.EntityFrameworkCore 2.2.1 directly to project 'WEB' to resolve this issue

When I am trying to install that version it says

Package restore failed. Rolling back package changes for 'WEB'

I can also mention that when I add reference BL to my project, it also includes DAL , and CL itself, (and DAL contains Microsoft.EntityFrameworkCore (2.2.1), can't understand what's the problem, any ideas?

Additional Images of the problem in here .

project.csproj

<Project Sdk="Microsoft.NET.Sdk.Web">
  <PropertyGroup>
    <TargetFramework>netcoreapp2.1</TargetFramework>
    <AspNetCoreHostingModel>InProcess</AspNetCoreHostingModel>
</PropertyGroup>

<ItemGroup>
<PackageReference Include="Microsoft.AspNetCore.App" />
</ItemGroup>

<ItemGroup>
<ProjectReference Include="..\CL\CL.csproj" />
</ItemGroup>

</Project>

i have added CL reference as you can see, now i want to add BL reference and get this error

Answer 1

The issue is because you're having local directory path to one of your {projectName}.csproj file Kindly review your .csproj files by Right clicking project and select Edit {projectName}.scproj

eg

<Reference Include="Microsoft.EntityFrameworkCore">
      <HintPath>..\..\..\..\..\..\..\Program Files\dotnet\sdk\NuGetFallbackFolder\Microsoft.EntityFrameworkCore\2.1.1\lib\netstandard2.0\Microsoft.EntityFrameworkCore.dll</HintPath>
    </Reference>

If yes than go to Nuget Package Manager and add your library bu selecting nuget.org as Package Source

after restoring from nuget Package manager csproject file will have following tag Added to

<PackageReference Include="Microsoft.Extensions.Identity.Stores" Version="2.1.1" />

Here {projectName} is the name of C# project.

Answer 2

Just want to chip in that i had the same issue but with EntityFrameworkCore 3.0 preview. I solved it by simply downgrading all entityframework 3.0(preview) nuget packages to latest stable (2.2).

Hopefully this helps someone aswell, took me hours...

Answer 3

Option 1 check visual studio error window and identify which package is making the conflict . make sure both packages have save version code