问题遇到的现象和发生背景
Win10+Unity+VSCode没办法代码补全QWQ
问题相关代码，请勿粘贴截图
运行结果及报错内容
Starting OmniSharp server at 2022/1/26下午10:48:19
Target: d:\UnityProject\Unity\Unity.sln
OmniSharp server started.
Path: c:\Users\Administrator\.vscode\extensions\ms-dotnettools.csharp-1.24.0\.omnisharp\1.38.1-beta.55\OmniSharp.exe
PID: 8424
[info]: OmniSharp.Stdio.Host
Starting OmniSharp on Windows 6.2.9200.0 (x64)
[info]: OmniSharp.Services.DotNetCliService
Checking the 'DOTNET_ROOT' environment variable to find a .NET SDK
[info]: OmniSharp.Services.DotNetCliService
Using the 'dotnet' on the PATH.
[info]: OmniSharp.Services.DotNetCliService
DotNetPath set to dotnet
[info]: OmniSharp.MSBuild.Discovery.MSBuildLocator
Located 1 MSBuild instance(s)
1: StandAlone 17.1.0 - "c:\Users\Administrator\.vscode\extensions\ms-dotnettools.csharp-1.24.0\.omnisharp\1.38.1-beta.55\.msbuild\Current\Bin"
[info]: OmniSharp.MSBuild.Discovery.MSBuildLocator
MSBUILD_EXE_PATH environment variable set to 'c:\Users\Administrator\.vscode\extensions\ms-dotnettools.csharp-1.24.0\.omnisharp\1.38.1-beta.55\.msbuild\Current\Bin\MSBuild.exe'
[info]: OmniSharp.MSBuild.Discovery.MSBuildLocator
Registered MSBuild instance: StandAlone 17.1.0 - "c:\Users\Administrator\.vscode\extensions\ms-dotnettools.csharp-1.24.0\.omnisharp\1.38.1-beta.55\.msbuild\Current\Bin"
CscToolExe = csc.exe
CscToolPath = c:\Users\Administrator\.vscode\extensions\ms-dotnettools.csharp-1.24.0\.omnisharp\1.38.1-beta.55\.msbuild\Current\Bin\Roslyn
MSBuildExtensionsPath = c:\Users\Administrator\.vscode\extensions\ms-dotnettools.csharp-1.24.0\.omnisharp\1.38.1-beta.55\.msbuild
MSBuildToolsPath = c:\Users\Administrator\.vscode\extensions\ms-dotnettools.csharp-1.24.0\.omnisharp\1.38.1-beta.55\.msbuild\Current\Bin
[info]: OmniSharp.WorkspaceInitializer
Invoking Workspace Options Provider: OmniSharp.Roslyn.CSharp.Services.CSharpFormattingWorkspaceOptionsProvider, Order: 0
[info]: OmniSharp.WorkspaceInitializer
Invoking Workspace Options Provider: OmniSharp.Roslyn.CSharp.Services.RenameWorkspaceOptionsProvider, Order: 100
[info]: OmniSharp.WorkspaceInitializer
Invoking Workspace Options Provider: OmniSharp.Roslyn.CSharp.Services.ImplementTypeWorkspaceOptionsProvider, Order: 110
[info]: OmniSharp.Cake.CakeProjectSystem
Detecting Cake files in 'd:\UnityProject\Unity'.
[info]: OmniSharp.Cake.CakeProjectSystem
Did not find any Cake files
[info]: OmniSharp.MSBuild.ProjectSystem
Detecting projects in 'd:\UnityProject\Unity\Unity.sln'.
[info]: OmniSharp.MSBuild.ProjectManager
Queue project update for 'd:\UnityProject\Unity\Assembly-CSharp.csproj'
[info]: OmniSharp.Script.ScriptProjectSystem
Detecting CSX files in 'd:\UnityProject\Unity'.
[info]: OmniSharp.Script.ScriptProjectSystem
Did not find any CSX files
[info]: OmniSharp.WorkspaceInitializer
Configuration finished.
[info]: OmniSharp.Stdio.Host
Omnisharp server running using Stdio at location 'd:\UnityProject\Unity' on host 8700.
[info]: OmniSharp.MSBuild.ProjectManager
Loading project: d:\UnityProject\Unity\Assembly-CSharp.csproj
[info]: OmniSharp.OmniSharpWorkspace
Miscellaneous file: d:\UnityProject\Unity\Assets\NewBehaviourScript.cs added to workspace
[fail]: OmniSharp.MSBuild.ProjectLoader
The reference assemblies for .NETFramework,Version=v4.7.1 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 'd:\UnityProject\Unity\Assembly-CSharp.csproj'.
d:\UnityProject\Unity\Assembly-CSharp.csproj
c:\Users\Administrator\.vscode\extensions\ms-dotnettools.csharp-1.24.0\.omnisharp\1.38.1-beta.55\.msbuild\Current\Bin\Microsoft.Common.CurrentVersion.targets(1220,5): Error: The reference assemblies for .NETFramework,Version=v4.7.1 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
[fail]: OmniSharp.MSBuild.ProjectManager
Attempted to update project that is not loaded: d:\UnityProject\Unity\Assembly-CSharp.csproj
我的解答思路和尝试过的方法
我尝试了一切办法，无果
比如说安装.net4.7.1QWQ
