美好的一天，

我试图在VS Code中的ASP.NET Core Blazor应用程序中添加一个名为“ microsoft.EntityFrameworkCore.SqlServer --version 3.0.0”的程序包。但是我收到以下错误。

P.s。这是我第一次使用VS Code。

终端

g:\Workspace\Test>dotnet add package microsoft.EntityFrameworkCore.SqlServer --version 3.0.0
  Writing C:\Users\dell\AppData\Local\Temp\tmpDB70.tmp
info : Adding PackageReference for package 'microsoft.EntityFrameworkCore.SqlServer' into project 'g:\Workspace\Test\Test.csproj'.
info : Restoring packages for g:\Workspace\Test\Test.csproj...
error: Unable to resolve 'microsoft.EntityFrameworkCore.SqlServer (>= 3.0.0)' for '.NETCoreApp,Version=v3.0'.
error: Package 'microsoft.EntityFrameworkCore.SqlServer' is incompatible with 'all' frameworks in project 'g:\Workspace\Test\Test.csproj'.

.NET信息

g:\Workspace\Test>dotnet --info
.NET Core SDK (reflecting any global.json):
 Version:   3.0.100
 Commit:    04339c3a26

Runtime Environment:
 OS Name:     Windows
 OS Version:  6.1.7601
 OS Platform: Windows
 RID:         win7-x64
 Base Path:   C:\Program Files\dotnet\sdk\3.0.100\

Host (useful for support):
  Version: 3.0.0
  Commit:  95a0a61858

.NET Core SDKs installed:
  3.0.100 [C:\Program Files\dotnet\sdk]

.NET Core runtimes installed:
  microsoft.AspNetCore.App 3.0.0 [C:\Program Files\dotnet\shared\microsoft.AspNetCore.App]
  microsoft.NETCore.App 3.0.0 [C:\Program Files\dotnet\shared\microsoft.NETCore.App]
  microsoft.WindowsDesktop.App 3.0.0 [C:\Program Files\dotnet\shared\microsoft.WindowsDesktop.App]

To install additional .NET Core runtimes or SDKs:
  https://aka.ms/dotnet-download

.csproj

<Project Sdk="microsoft.NET.Sdk.Web">

  <PropertyGroup>
    <TargetFramework>netcoreapp3.0</TargetFramework>
  </PropertyGroup>

</Project>

一些帖子建议我清除Nuget缓存。但还是徒劳。

 g:\Workspace\Test>dotnet nuget locals all --clear
    info : Clearing NuGet HTTP cache: C:\Users\dell\AppData\Local\NuGet\v3-cache
    info : Clearing NuGet global packages folder: C:\Users\dell\.nuget\packages\
    info : Clearing NuGet Temp cache: C:\Users\dell\AppData\Local\Temp\NuGetScratch
    info : Clearing NuGet plugins cache: C:\Users\dell\AppData\Local\NuGet\plugins-cache
    info : Local resources cleared.

    g:\Workspace\Test>dotnet restore --force
      Restore completed in 50.68 ms for g:\Workspace\Test\Test.csproj.

谢谢。