VS2017 MSBuildWorkspace无法使用转换后的ASP.Net Core Web应用程序打开解决方案

Question

我已经使用Microsoft.CodeAnalysis软件包设置了一些解决方案健全性测试，一切顺利，我安装了VS2017并转换了我的ASP.Net Core Web应用程序。 由于csproj文件简化（ https://blogs.msdn.microsoft.com/dotnet/2016/12/12/updating-visual-studio-2017-rc-net-core-tooling-improvements/ ），似乎解决方案不能再打开了。 我使用的代码如下：

var workspace = MSBuildWorkspace.Create();
var solution = workspace.OpenSolutionAsync(slnPath).Result;

这是我得到的例外：

Microsoft.Build.Exceptions.InvalidProjectFileException
The default XML namespace of the project must be the MSBuild XML namespace. If the project is authored in the MSBuild 2003 format, please add xmlns="http://schemas.microsoft.com/developer/msbuild/2003" to the <Project> element. If the project has been authored in the old 1.0 or 1.2 format, please convert it to MSBuild 2003 format.
   at Microsoft.Build.Shared.ProjectErrorUtilities.ThrowInvalidProject(String errorSubCategoryResourceName, IElementLocation elementLocation, String resourceName, Object[] args)
   at Microsoft.Build.Construction.ProjectParser.Parse()
   at Microsoft.Build.Construction.ProjectParser.Parse(XmlDocumentWithLocation document, ProjectRootElement projectRootElement)
   at Microsoft.Build.Construction.ProjectRootElement.Create(XmlReader xmlReader, ProjectCollection projectCollection)
   at Microsoft.CodeAnalysis.MSBuild.ProjectFileLoader.<LoadProjectAsync>d__5.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.CodeAnalysis.MSBuild.ProjectFileLoader.<LoadProjectFileAsync>d__3.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.CodeAnalysis.MSBuild.MSBuildProjectLoader.<LoadProjectAsync>d__23.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.CodeAnalysis.MSBuild.MSBuildProjectLoader.<GetOrLoadProjectAsync>d__22.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.CodeAnalysis.MSBuild.MSBuildProjectLoader.<LoadSolutionInfoAsync>d__18.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.CodeAnalysis.MSBuild.MSBuildWorkspace.<OpenSolutionAsync>d__18.MoveNext()

在我看来，新的csproj结构并不完全支持。 一个可能的解决方案可能是在没有转换项目的情况下创建单独的解决方案，但它确实是一种解决方法。 有任何想法吗？

编辑：

我试图按照错误消息中的建议，即添加xmlns属性，如下所示：

<Project Sdk="Microsoft.NET.Sdk.Web" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
  <PropertyGroup>
    <TargetFramework>net452</TargetFramework>
    <RuntimeIdentifier>win7-x86</RuntimeIdentifier>
    <GenerateDocumentationFile>true</GenerateDocumentationFile>
    <PreserveCompilationContext>true</PreserveCompilationContext>
    <AssemblyName>Arcmedia.Esl.WebApp.Api</AssemblyName>
    <OutputType>Exe</OutputType>
    <PackageId>Arcmedia.Esl.WebApp.Api</PackageId>
  </PropertyGroup>
  <ItemGroup>
    <None Include="App.config" />
    <Content Update="wwwroot;web.config">
      <CopyToPublishDirectory>PreserveNewest</CopyToPublishDirectory>
    </Content>
  </ItemGroup>
  <ItemGroup>
    <PackageReference Include="Microsoft.AspNetCore.Hosting" Version="1.1.0" />
    <PackageReference Include="Microsoft.AspNetCore.Hosting.Abstractions" Version="1.1.0" />
    <PackageReference Include="Microsoft.AspNetCore.Server.IISIntegration" Version="1.1.0" />
    <PackageReference Include="Microsoft.AspNetCore.Server.Kestrel" Version="1.1.0" />
  </ItemGroup>
  <ItemGroup Condition=" '$(TargetFramework)' == 'net452' ">
    <Reference Include="System" />
    <Reference Include="Microsoft.CSharp" />
  </ItemGroup>
  <ItemGroup>
    <ProjectReference Include="..\xyz\abc.def.csproj" />
  </ItemGroup>
</Project>

但这并没有解决问题，因为现在我得到另一个例外：

Microsoft.Build.Exceptions.InvalidProjectFileException
The attribute "Update" in element <Content> is unrecognized.
   at Microsoft.Build.Shared.ProjectErrorUtilities.ThrowInvalidProject(String errorSubCategoryResourceName, IElementLocation elementLocation, String resourceName, Object[] args)
   at Microsoft.Build.Internal.ProjectXmlUtilities.ThrowProjectInvalidAttribute(XmlAttributeWithLocation attribute)
   at Microsoft.Build.Internal.ProjectXmlUtilities.VerifyThrowProjectAttributes(XmlElementWithLocation element, String[] validAttributes)
   at Microsoft.Build.Construction.ProjectParser.ParseProjectItemElement(XmlElementWithLocation element, ProjectItemGroupElement parent)
   at Microsoft.Build.Construction.ProjectParser.ParseProjectItemGroupElement(XmlElementWithLocation element, ProjectElementContainer parent)
   at Microsoft.Build.Construction.ProjectParser.ParseProjectRootElementChildren(XmlElementWithLocation element)
   at Microsoft.Build.Construction.ProjectParser.Parse()
   at Microsoft.Build.Construction.ProjectParser.Parse(XmlDocumentWithLocation document, ProjectRootElement projectRootElement)
   at Microsoft.Build.Construction.ProjectRootElement.Create(XmlReader xmlReader, ProjectCollection projectCollection)
   at Microsoft.CodeAnalysis.MSBuild.ProjectFileLoader.<LoadProjectAsync>d__5.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.CodeAnalysis.MSBuild.ProjectFileLoader.<LoadProjectFileAsync>d__3.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.CodeAnalysis.MSBuild.MSBuildProjectLoader.<LoadProjectAsync>d__23.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.CodeAnalysis.MSBuild.MSBuildProjectLoader.<GetOrLoadProjectAsync>d__22.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.CodeAnalysis.MSBuild.MSBuildProjectLoader.<LoadSolutionInfoAsync>d__18.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.CodeAnalysis.MSBuild.MSBuildWorkspace.<OpenSolutionAsync>d__18.MoveNext()

所以，回到我原来的结论，似乎在尝试使用Microsoft.CodeAnalysis.MSBuild.MSBuildWorkspace.OpenSolutionAsync时，没有正确支持新的简化csproj文件结构。

Answer 1

问题出现是因为项目文件正在使用VS2017 csproj的新架构格式，但msbuild正在您的计算机上从较旧的安装（可能是VS2015）运行。 发生这种情况是因为您拥有的Roslyn MSBuildWorkspace是针对以前版本的MSBuild API构建的，该版本不了解新格式并且在您的计算机上使用该版本而不是更新版本。 如果您在计算机上没有旧版本，则MSBuildWorkspace会立即因类型加载异常而失败。

MSBuildWorkspace已经更新到较新的VS2017版本，但它还没有在nuget上。 您可以从Roslyn myget Feed中获取。

有关更多详细信息，请查看此github问题： https ： //github.com/dotnet/roslyn/issues/16886