error loading MSBuildWorkspace for projects containing .xaml files

[ltcmelo]

Version Used: 3.6.0

I'm unable to correctly OpenSolutionAsync through MSBuildWorkspace when a project contains .xaml files. I get the following load failure:

 Msbuild failed when processing the file 'C:\...\Name.csproj' with message: C:\WINDOWS\Microsoft.NET\Framework\v4.0.30319\Microsoft.WinFx.targets: (268, 9): Unknown build error, 'Object reference not set to an instance of an object.'

Which consequently leads to compilation errors like:

C:\..\MainWindow.xaml.cs(25,13): error CS0103: The name 'InitializeComponent' does not exist in the current context

I've found this and this old issues (from 2015) that look the same as the one I'm facing. These, along with additional resources I've found online, suggest the setting the MSBuild properties DesignTimeBuild and BuildingInsideVisualStudio to true (in the dictionary that's passed to MSBuildWorkspace.Create would fix the issue. However, it seems that those properties are already set by default in the newer MSBuildWorkspace versions (I'm using 3.6.0), so they didn't have any effect.

Other things I've tried as well:

• setting CheckForSystemRuntimeDependency to true;
• setting ws.LoadMetadataForReferencedProjects to true (where ws is the workspace created).

None of the above helped.

This is a snippet of how the .csproj includes the .xaml content.

<ItemGroup>
    <Compile Include="MainWindow.xaml.cs" />
    ...
</ItemGroup>
<ItemGroup>
    <Page Include="MainWindow.xaml">
        <Generator>MSBuild:Compile</Generator>
        <SubType>Designer</SubType>
    </Page>
</ItemGroup>

An invocation of msbuild.exe from the command line successfully builds the project.

What's the recommendation to deal with this kind of artefacts in a project? (I'd accept a "unorthodox" way of compiling the hidden .g.i.cs files, as long as it's robust/reliable).

[softwaretirol]

I would be intrested too,.. i could successfully emit an assembly out of a project which is .NET Core based and contains some XAML Files if I am passing "BuildingInsideVisualStudio".

In this case, the ".g.cs" files are getting generated, but i am missing the resource files with the compiled (B)XAML content? In case I am removing the "BuildingInsideVisualStudio", i got the same exception as @ltcmelo

using var workspace = MSBuildWorkspace.Create(new Dictionary<string, string>()
{
    { "BuildingInsideVisualStudio", "true" }
});
workspace.WorkspaceFailed += (o, e) => Console.WriteLine(e.Diagnostic.Message);
workspace.LoadMetadataForReferencedProjects = true;
var project = await workspace.OpenProjectAsync(sourceProject, new ConsoleLogger());
var compilation = await project.GetCompilationAsync();
var res = compilation.Emit("Test.exe");

[bert2]

I'm using 3.7.0 and I've hit the same issue. I got passed that NRE, but ran into another error. This property helps (source):

var workspace = MSBuildWorkspace.Create(new Dictionary<string, string> {
    ["AlwaysCompileMarkupFilesInSeparateDomain"] = "false"
});

The new error is:

[Failure] Msbuild failed when processing the file 'D:\DEV\microscope\src\VSExtension\VSExtension.csproj' with message: C:\WINDOWS\Microsoft.NET\Framework\v4.0.30319\Microsoft.WinFx.targets: (268, 9): Unknown build error, 'Could not load file or assembly 'Microsoft.CodeAnalysis.Workspaces, Version=3.7.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. Could not find or load a specific file. (Exception from HRESULT: 0x80131621)' .

Running the build task "manually" might help.

Fortunately for me, I can just move my XAML files into a different project, because I don't actually have to compile them with the MSBuildWorkspace. Good luck to you as this looks like a very messy situation...