VS Code C# Not Working With ,NET Framework 4.x

Environment data

dotnet --info output: .NET Core SDK (reflecting any global.json): Version: 2.2.101 Commit: 236713b0b7

Runtime Environment: OS Name: Windows OS Version: 10.0.16299 OS Platform: Windows RID: win10-x64 Base Path: C:\Program Files\dotnet\sdk\2.2.101\

Host (useful for support): Version: 2.2.0 Commit: 1249f08fed

.NET Core SDKs installed: 2.2.101 [C:\Program Files\dotnet\sdk]

.NET Core runtimes installed: Microsoft.AspNetCore.All 2.2.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All] Microsoft.AspNetCore.App 2.2.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App] Microsoft.NETCore.App 2.2.0 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]

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

VS Code version:1.30.1 C# Extension version:1.17.1

################### OmiCharp Output ################

Starting OmniSharp server at 1/5/2019, 10:45:03 AM
    Target: c:\Users\Public\Documents\Unity Projects\New\New.sln

OmniSharp server started.
    Path: C:\Users\Sahand\.vscode\extensions\ms-vscode.csharp-1.17.1\.omnisharp\1.32.8\OmniSharp.exe
    PID: 11972

[info]: OmniSharp.Stdio.Host
        Starting OmniSharp on Windows 6.2.9200.0 (x64)
[info]: OmniSharp.Services.DotNetCliService
        DotNetPath set to dotnet
[info]: OmniSharp.MSBuild.Discovery.MSBuildLocator
        Located 1 MSBuild instance(s)
            1: StandAlone 15.0 - "C:\Users\Sahand\.vscode\extensions\ms-vscode.csharp-1.17.1\.omnisharp\1.32.8\msbuild\15.0\Bin"
[info]: OmniSharp.MSBuild.Discovery.MSBuildLocator
        MSBUILD_EXE_PATH environment variable set to 'C:\Users\Sahand\.vscode\extensions\ms-vscode.csharp-1.17.1\.omnisharp\1.32.8\msbuild\15.0\Bin\MSBuild.exe'
[info]: OmniSharp.MSBuild.Discovery.MSBuildLocator
        Registered MSBuild instance: StandAlone 15.0 - "C:\Users\Sahand\.vscode\extensions\ms-vscode.csharp-1.17.1\.omnisharp\1.32.8\msbuild\15.0\Bin"
            CscToolExe = csc.exe
            CscToolPath = C:\Users\Sahand\.vscode\extensions\ms-vscode.csharp-1.17.1\.omnisharp\1.32.8\msbuild\15.0\Bin\Roslyn
            MSBuildExtensionsPath = C:\Users\Sahand\.vscode\extensions\ms-vscode.csharp-1.17.1\.omnisharp\1.32.8\msbuild
            MSBuildToolsPath = C:\Users\Sahand\.vscode\extensions\ms-vscode.csharp-1.17.1\.omnisharp\1.32.8\msbuild\15.0\Bin
[info]: OmniSharp.Cake.CakeProjectSystem
        Detecting Cake files in 'c:\Users\Public\Documents\Unity Projects\New'.
[info]: OmniSharp.Cake.CakeProjectSystem
        Could not find any Cake files
[info]: OmniSharp.WorkspaceInitializer
        Project system 'OmniSharp.DotNet.DotNetProjectSystem' is disabled in the configuration.
[info]: OmniSharp.MSBuild.ProjectSystem
        Detecting projects in 'c:\Users\Public\Documents\Unity Projects\New\New.sln'.
[info]: OmniSharp.MSBuild.ProjectManager
        Queue project update for 'c:\Users\Public\Documents\Unity Projects\New\Assembly-CSharp.csproj'
[info]: OmniSharp.Script.ScriptProjectSystem
        Detecting CSX files in 'c:\Users\Public\Documents\Unity Projects\New'.
[info]: OmniSharp.Script.ScriptProjectSystem
        Could not find any CSX files
[info]: OmniSharp.WorkspaceInitializer
        Invoking Workspace Options Provider: OmniSharp.Roslyn.CSharp.Services.CSharpWorkspaceOptionsProvider
[info]: OmniSharp.MSBuild.ProjectManager
        Loading project: c:\Users\Public\Documents\Unity Projects\New\Assembly-CSharp.csproj
[info]: OmniSharp.WorkspaceInitializer
        Configuration finished.
[info]: OmniSharp.Stdio.Host
        Omnisharp server running using Stdio at location 'c:\Users\Public\Documents\Unity Projects\New' on host 1144.
[fail]: OmniSharp.MSBuild.ProjectLoader
        The reference assemblies for framework ".NETFramework,Version=v4.5" were not found. To resolve this, install the SDK or Targeting Pack for this framework version or retarget your application to a version of the framework for which you have the SDK or Targeting Pack installed. Note that assemblies will be resolved from the Global Assembly Cache (GAC) and will be used in place of reference assemblies. Therefore your assembly may not be correctly targeted for the framework you intend.
[warn]: OmniSharp.MSBuild.ProjectManager
        Failed to load project file 'c:\Users\Public\Documents\Unity Projects\New\Assembly-CSharp.csproj'.
c:\Users\Public\Documents\Unity Projects\New\Assembly-CSharp.csproj
C:\Users\Sahand\.vscode\extensions\ms-vscode.csharp-1.17.1\.omnisharp\1.32.8\msbuild\15.0\Bin\Microsoft.Common.CurrentVersion.targets(1126,5): Error: The reference assemblies for framework ".NETFramework,Version=v4.5" were not found. To resolve this, install the SDK or Targeting Pack for this framework version or retarget your application to a version of the framework for which you have the SDK or Targeting Pack installed. Note that assemblies will be resolved from the Global Assembly Cache (GAC) and will be used in place of reference assemblies. Therefore your assembly may not be correctly targeted for the framework you intend.

[fail]: OmniSharp.MSBuild.ProjectManager
        Attemped to update project that is not loaded: c:\Users\Public\Documents\Unity Projects\New\Assembly-CSharp.csproj

[zhengjianhua91]

i had solved it 1.visit https://dotnet.microsoft.com/download/visual-studio-sdks?utm_source=getdotnetsdk&utm_medium=referral 2.download .NET Framework4.x Developer Pack and install

[filipw]

The solution is:

• on Windows - download the relevant .NET Framework4.x.x Developer Pack
• on Linux/MacOS - download latest Mono https://www.mono-project.com/download/stable/https://www.mono-project.com/download/stable/

If you are using C# Extension 1.23.1 please make sure that global Mono is correctly used - see https://github.com/OmniSharp/omnisharp-vscode/issues/4007#issuecomment-677405332