The reference assemblies for .NETFramework,Version=v4.8 were not found

[onionpsy]

Environment data

.csproj contain <TargetFrameworkVersion>v4.8</TargetFrameworkVersion>

dotnet --info output:

.NET Core SDK (reflecting any global.json):
 Version:   3.1.402
 Commit:    9b5de826fd

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.18362
 OS Platform: Windows
 RID:         win10-x64
 Base Path:   E:\Program Files\dotnet\sdk\3.1.402\

Host (useful for support):
  Version: 3.1.8
  Commit:  9c1330dedd

.NET Core SDKs installed:
  2.1.517 [E:\Program Files\dotnet\sdk]
  2.1.518 [E:\Program Files\dotnet\sdk]
  3.1.402 [E:\Program Files\dotnet\sdk]

.NET Core runtimes installed:
  Microsoft.AspNetCore.All 2.1.21 [E:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.22 [E:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.App 2.1.21 [E:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.22 [E:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.1.8 [E:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 2.1.21 [E:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.22 [E:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.1.8 [E:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.WindowsDesktop.App 3.1.8 [E:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

To install additional .NET Core runtimes or SDKs:
  https://aka.ms/dotnet-download

VS Code version: 1.48.2
C# Extension version: 1.23.2

OmniSharp log

[info]: OmniSharp.WorkspaceInitializer
        Invoking Workspace Options Provider: OmniSharp.Roslyn.CSharp.Services.BlockStructureWorkspaceOptionsProvider, Order: 140
[info]: OmniSharp.WorkspaceInitializer
        Configuration finished.
[info]: OmniSharp.Stdio.Host
        Omnisharp server running using Stdio at location 'e:\DATA\Godot\Test' on host 6580.
[fail]: OmniSharp.MSBuild.ProjectLoader
        The reference assemblies for .NETFramework,Version=v4.8 were not found. To resolve this, install the Developer Pack (SDK/Targeting Pack) for this framework version or retarget your application. You can download .NET Framework Developer Packs at https://aka.ms/msbuild/developerpacks
[warn]: OmniSharp.MSBuild.ProjectManager
        Failed to load project file 'e:\DATA\Godot\Test\Test.csproj'.
e:\DATA\Godot\Test\Test.csproj
E:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\MSBuild\Current\Bin\Microsoft.Common.CurrentVersion.targets(1177,5): Error: The reference assemblies for .NETFramework,Version=v4.8 were not found. To resolve this, install the Developer Pack (SDK/Targeting Pack) for this framework version or retarget your application. You can download .NET Framework Developer Packs at https://aka.ms/msbuild/developerpacks

Steps to reproduce

• Install .NET 4.8 SDK + .NET targeting pack through Visual Studio Build Tools 2019 (16.7.3)
• Open a C# project that require .NET 4.8
• Install C#, C# tools for Godot extension on VScode,

I tried the workaround proposed here but same error.

Downgrading C# extension to 1.23.0 give me this error.

Godot has no problem building the project but I think it's an embedded Mono.

[jmarolf]

If this only reproduces on Godot projects, I am going to assume that it is an issue with their targets files.

[leontancfa]

I got the exact same error, too, when I load other projects. I think this issue is not closed.

[JoeRobich]

@leontancfa If you are using Windows and have VS or the Build Tools installed. I think you may need to do the following:

1. Open the Visual Studio Installer.
2. Choose to Modify your installation.
3. Choose the Individual Components tab.
4. Ensure that the 4.8 targeting pack is installed.