Matt Ward

NuGet Support in Visual Studio for Mac 17.3

Changes

  • NuGet 6.2.1 support
  • Improved NuGet restore support for a solution containing classic and SDK style projects
    • Fixed unable to find WorkloadAutoImportPropsLocator SDK restore error with classic and SDK style projects
    • Fixed invalid framework identifer restore error with classic and SDK style projects
    • Fixed error restoring Mapsui.Mac.sln

More information on all the new features and changes in Visual Studio for Mac 17.3 can be found in the release notes.

NuGet 6.2.1 support

NuGet 6.2.1.2 is now included with Visual Studio for Mac 17.3.

Improved NuGet restore support for a solution containing classic and SDK style projects

NuGet restore has been improved for a solution contains a mix of classic (non SDK style projects) and SDK style projects. Problems can occur in this case because classic projects require MSBuild on Mono, whilst SDK style projects typically require .NET MSBuild.

The following sections contain information about the individual problems that have been fixed in Visual Studio for Mac 17.3

Fixed unable to find WorkloadAutoImportPropsLocator SDK restore error with classic and SDK style projects

If a solution contained a .NET 6 project, and a .NET 4.7.2 SDK style project, and Building with MSBuild on Mono was unchecked in Solution Properties – Build – General, the restore would fail with an error when only .NET 6.0.300 SDK was installed:

Unable to find SDK 'Microsoft.NET.SDK.WorkloadAutoImportPropsLocator'

To fix this Visual Studio for Mac now does not load referenced projects when getting restore information for a specific project using its MSBuild host. When all projects were loaded by the MSBuild host, the project load would fail since the MSBuildSDKsPath was not defined because .NET SDK was being used since none supported using MSBuild on Mono.

Fixed invalid framework identifer restore error with classic and SDK style projects

If a solution contained a non-SDK style project then MSBuild on mono was always used to restore if the solution contained more than 10 projects. This prevented some solutions from being restored if they contained mix of .NET 6.0 projects and classic non-SDK style projects, and had a global.json that pinned the .NET SDK to 6.0.300. The restore would fail when MSBuild on mono was used with an error about an invalid framework identifier.

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MonoBundle/MSBuild/Current/bin/NuGet.targets(162,5):
error MSB4018: The "WriteRestoreGraphTask" task failed unexpectedly.
error MSB4018: NuGet.Frameworks.FrameworkException: Invalid framework identifier ''.
error MSB4018:   at NuGet.Frameworks.NuGetFramework.GetShortFolderName (NuGet.Frameworks.IFrameworkNameProvider mappings)
error MSB4018:   at NuGet.Frameworks.NuGetFramework.GetShortFolderName ()
error MSB4018:   at NuGet.ProjectModel.PackageSpecWriter.WriteMetadataTargetFrameworks (NuGet.RuntimeModel.IObjectWriter writer, NuGet.ProjectModel.ProjectRestoreMetadata msbuildMetadata)
error MSB4018:   at NuGet.ProjectModel.PackageSpecWriter.SetMSBuildMetadata (NuGet.RuntimeModel.IObjectWriter writer, NuGet.ProjectModel.PackageSpec packageSpec)

MSBuild on mono does not support .NET 6.0.300 sdk and, because of the global.json file, Visual Studio for Mac did not downgrade to an older supported .NET SDK which then caused the restore to fail since it cannot resolve the target framework.

To avoid this problem the restore now checks the Build with MSBuild on Mono setting, in Solution Properties – Build – General, and if unchecked the restore will succeed.

Fixed error restoring Mapsui.Mac.sln

The Mapsui.Mac.sln from https://github.com/Mapsui/Mapsui would fail to restore with following error when Build with MSBuild on Mono was disabled in Solution Properties:

error MSB4019: The imported project "/usr/local/share/dotnet/sdk/6.0.300/Xamarin/iOS/Xamarin.iOS.CSharp.targets" was not found.

The Mapsui.Mac.sln contains .NET 6.0 maui and some classic Xamarin projects. It is not possible to restore these all projects with either MSBuild on Mono or .NET’s MSBuild. The solution also contains more than 10 projects which results in Visual Studio for Mac running MSBuild directly out of process instead of using its MSBuild host. Since neither MSBuild on mono, nor .NET’s MSBuild can restore the solution, this would fail.

To fix this Visual Studio for Mac no longer runs MSBuild directly out of process to run the restore when a solution contains a mix of project types that require different MSBuild’s. Instead Visual Studio for Mac runs the restore with its MSBuild hosts, which support both MSBuild on Mono and .NET’s MSBuild. Each project then has the GenerateRestoreGraphFile MSBuild target run separately using the correct MSBuild. This requires the Build with MSBuild on Mono option to be unchecked, and allows the Mapsui.Mac.sln to be restored.