MSBuildWorkspace.Create() fails when pointing to the .NET 7 SDK from a .NET 6 project

[aronweiler]

Describe the bug

When referencing the the .NET 7 SDK via the MSBuildLocator prior to the call to MSBuildWorkspace.Create() in a .NET 6 project, the .Create() call fails as it is unable to load .NET 7 runtime assemblies.

Note

It is possible that this functions as intended... i.e. that you cannot create an MSBuild workspace using a newer SDK than the one that the project is compiled with. If that is the case, please close this issue. However, I have not been able to find any documentation that says explicitly that this should not work.

To Reproduce

Run the following code in a .NET 6 console application. (needs the Microsoft.Build.Locator and Microsoft.CodeAnalysis.Workspaces.MSBuild packages)

using Microsoft.Build.Locator;
using Microsoft.CodeAnalysis.MSBuild;

MSBuildLocator.RegisterMSBuildPath(@"C:\Program Files\dotnet\sdk\7.0.100");
var workspace = MSBuildWorkspace.Create();

Exceptions

Unhandled exception. System.Reflection.ReflectionTypeLoadException: Unable to load one or more of the requested types.
Could not load file or assembly 'System.Runtime, Version=7.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. The system cannot find the file specified.
Could not load file or assembly 'System.Runtime, Version=7.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. The system cannot find the file specified.
Could not load file or assembly 'System.Runtime, Version=7.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. The system cannot find the file specified.
Could not load file or assembly 'System.Runtime, Version=7.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. The system cannot find the file specified.
Could not load file or assembly 'System.Runtime, Version=7.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. The system cannot find the file specified.
Could not load file or assembly 'System.Runtime, Version=7.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. The system cannot find the file specified.
Could not load file or assembly 'System.Runtime, Version=7.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. The system cannot find the file specified.
   at System.Reflection.RuntimeModule.GetTypes(RuntimeModule module)
   at System.Reflection.RuntimeAssembly.get_DefinedTypes()
   at System.Composition.Hosting.ContainerConfiguration.<>c.<WithAssemblies>b__16_0(Assembly a)
   at System.Linq.Enumerable.SelectManySingleSelectorIterator`2.MoveNext()
   at System.Composition.TypedParts.TypedPartExportDescriptorProvider..ctor(IEnumerable`1 types, AttributedModelProvider attributeContext)
   at System.Composition.Hosting.ContainerConfiguration.CreateContainer()
   at Microsoft.CodeAnalysis.Host.Mef.MefHostServices.Create(IEnumerable`1 assemblies)
   at Microsoft.CodeAnalysis.Host.Mef.MSBuildMefHostServices.get_DefaultServices()
   at Microsoft.CodeAnalysis.MSBuild.MSBuildWorkspace.Create()
   at Program.<Main>$(String[] args) in C:\Repos\MSBuildWorkspaceSpike\MSBuildWorkspaceSpike\Program.cs:line 15
System.IO.FileNotFoundException: Could not load file or assembly 'System.Runtime, Version=7.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. The system cannot find the file specified.
File name: 'System.Runtime, Version=7.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'
System.IO.FileNotFoundException: Could not load file or assembly 'System.Runtime, Version=7.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. The system cannot find the file specified.
File name: 'System.Runtime, Version=7.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'
System.IO.FileNotFoundException: Could not load file or assembly 'System.Runtime, Version=7.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. The system cannot find the file specified.
File name: 'System.Runtime, Version=7.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'
System.IO.FileNotFoundException: Could not load file or assembly 'System.Runtime, Version=7.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. The system cannot find the file specified.
File name: 'System.Runtime, Version=7.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'
System.IO.FileNotFoundException: Could not load file or assembly 'System.Runtime, Version=7.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. The system cannot find the file specified.
File name: 'System.Runtime, Version=7.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'
System.IO.FileNotFoundException: Could not load file or assembly 'System.Runtime, Version=7.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. The system cannot find the file specified.
File name: 'System.Runtime, Version=7.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'
System.IO.FileNotFoundException: Could not load file or assembly 'System.Runtime, Version=7.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. The system cannot find the file specified.
File name: 'System.Runtime, Version=7.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'

Further technical details

C:\Windows\System32>dotnet --info
.NET SDK:
 Version:   7.0.100
 Commit:    e12b7af219

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.19044
 OS Platform: Windows
 RID:         win10-x64
 Base Path:   C:\Program Files\dotnet\sdk\7.0.100\

Host:
  Version:      7.0.0
  Architecture: x64
  Commit:       d099f075e4

.NET SDKs installed:
  1.1.10 [C:\Program Files\dotnet\sdk]
  1.1.14 [C:\Program Files\dotnet\sdk]
  2.1.202 [C:\Program Files\dotnet\sdk]
  2.1.402 [C:\Program Files\dotnet\sdk]
  2.1.521 [C:\Program Files\dotnet\sdk]
  2.1.811 [C:\Program Files\dotnet\sdk]
  5.0.100 [C:\Program Files\dotnet\sdk]
  6.0.100 [C:\Program Files\dotnet\sdk]
  7.0.100 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.All 2.1.4 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.23 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.25 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.30 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.App 2.1.4 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.23 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.25 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.30 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.1.31 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 5.0.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 5.0.17 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 6.0.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 6.0.11 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 7.0.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 1.0.12 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 1.0.16 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 1.1.9 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 1.1.13 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.0.9 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.4 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.23 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.25 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.30 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.1.31 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 5.0.0 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 5.0.17 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 6.0.0 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 6.0.11 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 7.0.0 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.WindowsDesktop.App 3.1.31 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 5.0.0 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 5.0.17 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 6.0.0 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 6.0.11 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 7.0.0 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

Other architectures found:
  x86   [C:\Program Files (x86)\dotnet]
    registered at [HKLM\SOFTWARE\dotnet\Setup\InstalledVersions\x86\InstallLocation]

Environment variables:
  Not set

global.json file:
  Not found

[dotnet-issue-labeler]

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

[aronweiler]

To add to this, when I run the MSBuildLocator.QueryVisualStudioInstances() command from a .NET 6 project, I don't see the .NET 7 SDK or path listed as I would expect (it's installed).

The output I get from MSBuildLocator.QueryVisualStudioInstances() is:

C:\Program Files\dotnet\sdk\6.0.100
C:\Program Files\dotnet\sdk\5.0.100
C:\Program Files\dotnet\sdk\2.1.811
C:\Program Files\dotnet\sdk\2.1.521
C:\Program Files\dotnet\sdk\2.1.402
C:\Program Files\dotnet\sdk\2.1.202
C:\Program Files\dotnet\sdk\1.1.14
C:\Program Files\dotnet\sdk\1.1.10

Running the same command from a .NET 7 project adds the following SDK:

C:\Program Files\dotnet\sdk\7.0.100

[baronfel]

The reason you don't see the 7.0 SDK when run from a 6.0 project using Locator is that Locator uses the runtime version of the executing application to limit the set of returned SDKs to presumable-compatible ones. You will need to retarget your application to net7.0 in order to use the 7.0 SDK toolchain.

[aronweiler]

Thanks @baronfel, that makes sense as to why the SDK does not show up in my list.

What about when I manually target the .NET 7 SDK using MSBuildLocator.RegisterMSBuildPath(...)? Should I not be capable of then creating an instance of the MSBuildWorkspace that targets the SDK I provide? Or does it presume that there is no forward compatibility?

[baronfel]

No, that won't work because by the time you're loading the MSBuild binaries from the 7.0 SDK (which have a dependency on 7.0 dlls) you're already running on a 6.0 .NET Runtime. That's why in your initial report the MSBuild libraries were erroring trying to load System.Runtime.

[aronweiler]

Ok, thanks. I'll mark this issue as closed, then, since my assumption about being able to load newer SDKs was incorrect.