关于c#：在.net核心控制台应用程序中使用.net类库时，项目构建失败

Project build failed while using .net class library in .net core console application

我有.Net Core 3.1控制台应用程序，它引用了作为参考添加的类库项目FxCore。
类库csproj具有<TargetFrameworks>net45;net451;net452;net46;net461;net462;net47;net471;net472</TargetFrameworks>，我尝试将其更改为<TargetFrameworks>net45;</TargetFrameworks>，但仍然遇到相同的错误。

我遇到以下错误。，我尝试清理->重新构建，重新打开Visual Studio 2019(版本16.5.2)

1>------ Build started: Project: FxCore, Configuration: Debug Any CPU
------ 1>J:\\Test\\core\\fx-core\\FxCore.csproj(3,3): warning MSB4011:"C:\\Program Files (x86)\\Microsoft Visual
Studio\\2019\\Professional\\MSBuild\\Current\\Microsoft.Common.props"
cannot be imported again. It was already imported at"C:\\Program
Files\\dotnet\\sdk\\3.1.201\\Sdks\\Microsoft.NET.Sdk\\Sdk\\Sdk.props (40,3)".
This is most likely a build authoring error. This subsequent import
will be ignored. 1>C:\\Program
Files\\dotnet\\sdk\\3.1.201\\Sdks\\Microsoft.NET.Sdk\\Sdk\\Sdk.targets(37,3):
warning MSB4011:"C:\\Program Files (x86)\\Microsoft Visual
Studio\\2019\\Professional\\MSBuild\\Current\\Bin\\Microsoft.CSharp.targets"
cannot be imported again. It was already imported at
"J:\\Test\\core\\fx-core\\FxCore.csproj (120,3)". This is most likely a
build authoring error. This subsequent import will be ignored.
1>C:\\Program Files (x86)\\Microsoft Visual
Studio\\2019\\Professional\\MSBuild\\Current\\Bin\\Microsoft.Common.CurrentVersion.targets(2081,5):
warning MSB3245: Could not resolve this reference. Could not locate
the assembly"FXEntity, Version=1.0.1.12, Culture=neutral,
processorArchitecture=MSIL". Check to make sure the assembly exists on
disk. If this reference is required by your code, you may get
compilation errors. 1>FxCore ->
J:\\Test\\core\\fx-core\\bin\\Debug\\FxCore.dll
1>J:\\Test\\core\\fx-core\\FxCore.csproj(3,3): warning MSB4011:
"C:\\Program Files (x86)\\Microsoft Visual
Studio\\2019\\Professional\\MSBuild\\Current\\Microsoft.Common.props"
cannot be imported again. It was already imported at"C:\\Program
Files\\dotnet\\sdk\\3.1.201\\Sdks\\Microsoft.NET.Sdk\\Sdk\\Sdk.props (40,3)".
This is most likely a build authoring error. This subsequent import
will be ignored. 1>C:\\Program
Files\\dotnet\\sdk\\3.1.201\\Sdks\\Microsoft.NET.Sdk\\Sdk\\Sdk.targets(37,3):
warning MSB4011:"C:\\Program Files (x86)\\Microsoft Visual
Studio\\2019\\Professional\\MSBuild\\Current\\Bin\\Microsoft.CSharp.targets"
cannot be imported again. It was already imported at
"J:\\Test\\core\\fx-core\\FxCore.csproj (120,3)". This is most likely a
build authoring error. This subsequent import will be ignored.
1>J:\\Test\\core\\fx-core\\FxCore.csproj(3,3): warning MSB4011:
"C:\\Program Files (x86)\\Microsoft Visual
Studio\\2019\\Professional\\MSBuild\\Current\\Microsoft.Common.props"
cannot be imported again. It was already imported at"C:\\Program
Files\\dotnet\\sdk\\3.1.201\\Sdks\\Microsoft.NET.Sdk\\Sdk\\Sdk.props (40,3)".
This is most likely a build authoring error. This subsequent import
will be ignored. 1>C:\\Program
Files\\dotnet\\sdk\\3.1.201\\Sdks\\Microsoft.NET.Sdk\\Sdk\\Sdk.targets(37,3):
warning MSB4011:"C:\\Program Files (x86)\\Microsoft Visual
Studio\\2019\\Professional\\MSBuild\\Current\\Bin\\Microsoft.CSharp.targets"
cannot be imported again. It was already imported at
"J:\\Test\\core\\fx-core\\FxCore.csproj (120,3)". This is most likely a
build authoring error. This subsequent import will be ignored.
1>J:\\Test\\core\\fx-core\\FxCore.csproj : warning NU1603: FxCore depends
on Microsoft.Practices.ServiceLocation (>= 1.3.0) but
Microsoft.Practices.ServiceLocation 1.3.0 was not found. An
approximate best match of Microsoft.Practices.ServiceLocation 1.4.11
was resolved. 1>Done building project"FxCore.csproj". 1>Done building
project"FxCore.csproj". 2>------ Build started: Project:
CoreConsoleApp, Configuration: Debug Any CPU ------
2>J:\\Test\\core\\fx-core\\FxCore.csproj(3,3): warning MSB4011:
"C:\\Program Files (x86)\\Microsoft Visual
Studio\\2019\\Professional\\MSBuild\\Current\\Microsoft.Common.props"
cannot be imported again. It was already imported at"C:\\Program
Files\\dotnet\\sdk\\3.1.201\\Sdks\\Microsoft.NET.Sdk\\Sdk\\Sdk.props (40,3)".
This is most likely a build authoring error. This subsequent import
will be ignored. 2>C:\\Program
Files\\dotnet\\sdk\\3.1.201\\Sdks\\Microsoft.NET.Sdk\\Sdk\\Sdk.targets(37,3):
warning MSB4011:"C:\\Program Files (x86)\\Microsoft Visual
Studio\\2019\\Professional\\MSBuild\\Current\\Bin\\Microsoft.CSharp.targets"
cannot be imported again. It was already imported at
"J:\\Test\\core\\fx-core\\FxCore.csproj (120,3)". This is most likely a
build authoring error. This subsequent import will be ignored.
2>C:\\Program Files (x86)\\Microsoft Visual
Studio\\2019\\Professional\\MSBuild\\Current\\Bin\\Microsoft.Common.CurrentVersion.targets(1655,5):
warning NU1702: ProjectReference 'J:\\Test\\core\\fx-core\\FxCore.csproj'
was resolved using '.NETFramework,Version=v4.6.1' instead of the
project target framework '.NETCoreApp,Version=v3.1'. This project may
not be fully compatible with your project.
2>J:\\Test\\core\\CoreConsoleApp\\Program.cs(2,7,2,9): error CS0246: The
type or namespace name 'FX' could not be found (are you missing a
using directive or an assembly reference?)
2>J:\\Test\\core\\CoreConsoleApp\\Program.cs(7,24,7,32): error CS0246: The
type or namespace name 'FxCommon' could not be found (are you missing
a using directive or an assembly reference?) 2>Done building project
"CoreConsoleApp.csproj" -- FAILED.
========== Build: 1 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

但是在Program.cs中，我可以使用代码，IntelliSense不会显示任何错误。

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using System;
using FX.Core;
namespace CoreConsoleApp
{
class Program
{
private static FxCommon _fxCommon = new FxCommon();
static void Main(string[] args)
{
Console.WriteLine("Hello World!");
_fxCommon.Logger.LogWrite("hello");
}
}
}

由于这个原因，我无法运行控制台应用程序，请提供帮助。