ServiceStack 和 AWS：创建了一个 ASP.NET 空项目，但无法在目标框架中选择 .NET Core

Question

I started a ServiceStack ASP.NET Empty project in VS2019, as that was the closest thing I could find to what I wanted. The template is right on, but I want to run it in .NET Core.

However, the Target framework was set to .NET Framework 4.5, but I wanted it to be .NET Core 2.1+, and I cannot select it either:

I know that I have .NET Core installed, because I have been developing a Blazor app also in VS2019, which is .NET Core.

I'd like to know what I am missing here.

Edit

Here is the csproj file for the project containing the AppHost.cs

<?xml version="1.0" encoding="utf-8"?>
<Project ToolsVersion="12.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
  <Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />
  <PropertyGroup>
    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
    <ProductVersion>
    </ProductVersion>
    <SchemaVersion>2.0</SchemaVersion>
    <ProjectGuid>{4389B305-B381-4B50-B1A8-BBB5259A0524}</ProjectGuid>
    <ProjectTypeGuids>{349c5851-65df-11da-9384-00065b846f21};{fae04ec0-301f-11d3-bf4b-00c04f79efbc}</ProjectTypeGuids>
    <OutputType>Library</OutputType>
    <AppDesignerFolder>Properties</AppDesignerFolder>
    <RootNamespace>DrivingLicenseApi</RootNamespace>
    <AssemblyName>DrivingLicenseApi</AssemblyName>
    <TargetFrameworkVersion>v4.5</TargetFrameworkVersion>
    <UseIISExpress>true</UseIISExpress>
    <IISExpressSSLPort />
    <IISExpressAnonymousAuthentication />
    <IISExpressWindowsAuthentication />
    <IISExpressUseClassicPipelineMode />
    <SolutionDir Condition="$(SolutionDir) == '' Or $(SolutionDir) == '*Undefined*'">..\..\</SolutionDir>
    <RestorePackages>true</RestorePackages>
    <Use64BitIISExpress />
    <UseGlobalApplicationHostFile />
  </PropertyGroup>
  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
    <DebugSymbols>true</DebugSymbols>
    <DebugType>full</DebugType>
    <Optimize>false</Optimize>
    <OutputPath>bin\</OutputPath>
    <DefineConstants>DEBUG;TRACE</DefineConstants>
    <ErrorReport>prompt</ErrorReport>
    <WarningLevel>4</WarningLevel>
  </PropertyGroup>
  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
    <DebugType>pdbonly</DebugType>
    <Optimize>true</Optimize>
    <OutputPath>bin\</OutputPath>
    <DefineConstants>TRACE</DefineConstants>
    <ErrorReport>prompt</ErrorReport>
    <WarningLevel>4</WarningLevel>
  </PropertyGroup>
  <ItemGroup>
    <Reference Include="Microsoft.CSharp" />
    <Reference Include="ServiceStack, Version=5.0.0.0, Culture=neutral, PublicKeyToken=02c12cbda47e6587, processorArchitecture=MSIL">
      <HintPath>..\..\packages\ServiceStack.5.6.0\lib\net45\ServiceStack.dll</HintPath>
    </Reference>
    <Reference Include="ServiceStack.Client, Version=5.0.0.0, Culture=neutral, PublicKeyToken=02c12cbda47e6587, processorArchitecture=MSIL">
      <HintPath>..\..\packages\ServiceStack.Client.5.6.0\lib\net45\ServiceStack.Client.dll</HintPath>
    </Reference>
    <Reference Include="ServiceStack.Common, Version=5.0.0.0, Culture=neutral, PublicKeyToken=02c12cbda47e6587, processorArchitecture=MSIL">
      <HintPath>..\..\packages\ServiceStack.Common.5.6.0\lib\net45\ServiceStack.Common.dll</HintPath>
    </Reference>
    <Reference Include="ServiceStack.Interfaces, Version=5.0.0.0, Culture=neutral, PublicKeyToken=02c12cbda47e6587, processorArchitecture=MSIL">
      <HintPath>..\..\packages\ServiceStack.Interfaces.5.6.0\lib\net45\ServiceStack.Interfaces.dll</HintPath>
    </Reference>
    <Reference Include="ServiceStack.OrmLite, Version=5.0.0.0, Culture=neutral, PublicKeyToken=02c12cbda47e6587, processorArchitecture=MSIL">
      <HintPath>..\..\packages\ServiceStack.OrmLite.5.6.0\lib\net45\ServiceStack.OrmLite.dll</HintPath>
    </Reference>
    <Reference Include="ServiceStack.Redis, Version=5.0.0.0, Culture=neutral, PublicKeyToken=02c12cbda47e6587, processorArchitecture=MSIL">
      <HintPath>..\..\packages\ServiceStack.Redis.5.6.0\lib\net45\ServiceStack.Redis.dll</HintPath>
    </Reference>
    <Reference Include="ServiceStack.Server, Version=5.0.0.0, Culture=neutral, PublicKeyToken=02c12cbda47e6587, processorArchitecture=MSIL">
      <HintPath>..\..\packages\ServiceStack.Server.5.6.0\lib\net45\ServiceStack.Server.dll</HintPath>
    </Reference>
    <Reference Include="ServiceStack.Text, Version=5.0.0.0, Culture=neutral, PublicKeyToken=02c12cbda47e6587, processorArchitecture=MSIL">
      <HintPath>..\..\packages\ServiceStack.Text.5.6.0\lib\net45\ServiceStack.Text.dll</HintPath>
    </Reference>
    <Reference Include="System.Buffers, Version=4.0.3.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51, processorArchitecture=MSIL">
      <HintPath>..\..\packages\System.Buffers.4.5.0\lib\netstandard1.1\System.Buffers.dll</HintPath>
    </Reference>
    <Reference Include="System.ComponentModel.DataAnnotations" />
    <Reference Include="System" />
    <Reference Include="System.Memory, Version=4.0.1.1, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51, processorArchitecture=MSIL">
      <HintPath>..\..\packages\System.Memory.4.5.3\lib\netstandard1.1\System.Memory.dll</HintPath>
    </Reference>
    <Reference Include="System.Net" />
    <Reference Include="System.Data" />
    <Reference Include="System.Core" />
    <Reference Include="System.Runtime.CompilerServices.Unsafe, Version=4.0.4.1, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
      <HintPath>..\..\packages\System.Runtime.CompilerServices.Unsafe.4.5.2\lib\netstandard1.0\System.Runtime.CompilerServices.Unsafe.dll</HintPath>
    </Reference>
    <Reference Include="System.ServiceModel" />
    <Reference Include="System.Web" />
    <Reference Include="System.Xml" />
    <Reference Include="System.Configuration" />
  </ItemGroup>
  <ItemGroup>
    <ProjectReference Include="..\DrivingLicenseApi.ServiceInterface\DrivingLicenseApi.ServiceInterface.csproj">
      <Project>{801a0f89-d5f6-49a6-bcea-6624388c98a4}</Project>
      <Name>DrivingLicenseApi.ServiceInterface</Name>
    </ProjectReference>
    <ProjectReference Include="..\DrivingLicenseApi.ServiceModel\DrivingLicenseApi.ServiceModel.csproj">
      <Project>{53E82AC1-DD1D-4C66-B55F-F9F4ACFB2F40}</Project>
      <Name>DrivingLicenseApi.ServiceModel</Name>
    </ProjectReference>
  </ItemGroup>
  <ItemGroup>
    <Content Include="packages.config" />
    <None Include="Web.Debug.config">
      <DependentUpon>Web.config</DependentUpon>
    </None>
    <None Include="Web.Release.config">
      <DependentUpon>Web.config</DependentUpon>
    </None>
  </ItemGroup>
  <ItemGroup>
    <Content Include="Global.asax" />
    <Content Include="Web.config" />
  </ItemGroup>
  <ItemGroup>
    <Compile Include="AppHost.cs" />
    <Compile Include="Global.asax.cs">
      <DependentUpon>Global.asax</DependentUpon>
    </Compile>
    <Compile Include="Properties\AssemblyInfo.cs" />
  </ItemGroup>
  <PropertyGroup>
    <VisualStudioVersion Condition="'$(VisualStudioVersion)' == ''">10.0</VisualStudioVersion>
    <VSToolsPath Condition="'$(VSToolsPath)' == ''">$(MSBuildExtensionsPath32)\Microsoft\VisualStudio\v$(VisualStudioVersion)</VSToolsPath>
  </PropertyGroup>
  <Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" />
  <Import Project="$(VSToolsPath)\WebApplications\Microsoft.WebApplication.targets" Condition="'$(VSToolsPath)' != ''" />
  <Import Project="$(MSBuildExtensionsPath32)\Microsoft\VisualStudio\v10.0\WebApplications\Microsoft.WebApplication.targets" Condition="false" />
  <Import Project="$(SolutionDir)\.nuget\NuGet.targets" Condition="Exists('$(SolutionDir)\.nuget\NuGet.targets')" />
  <ProjectExtensions>
    <VisualStudio>
      <FlavorProperties GUID="{349c5851-65df-11da-9384-00065b846f21}">
        <WebProjectProperties>
          <UseIIS>True</UseIIS>
          <AutoAssignPort>True</AutoAssignPort>
          <DevelopmentServerPort>51893</DevelopmentServerPort>
          <DevelopmentServerVPath>/</DevelopmentServerVPath>
          <IISUrl>http://localhost:51893/</IISUrl>
          <NTLMAuthentication>False</NTLMAuthentication>
          <UseCustomServer>False</UseCustomServer>
          <CustomServerUrl>
          </CustomServerUrl>
          <SaveServerSettingsInUserFile>False</SaveServerSettingsInUserFile>
        </WebProjectProperties>
      </FlavorProperties>
    </VisualStudio>
  </ProjectExtensions>
  <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 
       Other similar extension points exist, see Microsoft.Common.targets.
  <Target Name="BeforeBuild">
  </Target>
  <Target Name="AfterBuild">
  </Target>
  -->
</Project>

Answer 1

ServiceStackVS VS.NET Extension only lets you create .NET Framework projects.

To create ASP.NET Core projects you need to use web new , eg to create an Empty ASP.NET Core project run:

$ web new web ProjectName

Answer 2

Try to open your .csproj for editing and put netcoreapp2.1 as your target framework.

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

Check what version of .NET Core is installed globally by running dotnet --version from your cmd.