VS2017-“ .NET Standard 2.0”没有目标

如何解决VS2017-“ .NET Standard 2.0”没有目标

当前，我无法在使用VS2017的开发人员计算机上编译任何.NET Standard 2.0项目。构建因以下错误而停止：

error : The current .NET SDK does not support targeting .NET Standard 2.0.  Either target .NET Standard 1.6 or lower,or use a version of the .NET SDK that supports .NET Standard 2.0.

使用VS2019，可以毫无问题地构建项目（同一台机器）。 上周，一切也都可以在VS2017上正常运行（我已经在VS2017上创建了该项目）。

我尝试重新安装VS2017（不成功）并重新安装.NET Core SDK（不成功）。

这是“ dotnet --info”的当前输出

C:\Program Files (x86)\Microsoft Visual Studio\2017\Enterprise>dotnet --info
.NET Core SDK (gemäß "global.json"):
Version:   3.1.401
Commit:    5b6f5e5005

Laufzeitumgebung:
 OS Name:     Windows
 OS Version:  10.0.18363
 OS Platform: Windows
 RID:         win10-x64
 Base Path:   C:\Program Files\dotnet\sdk\3.1.401\

Host (useful for support):
  Version: 3.1.7
  Commit:  fcfdef8d6b

.NET Core SDKs installed:
  1.1.13 [C:\Program Files\dotnet\sdk]
  2.1.517 [C:\Program Files\dotnet\sdk]
  2.2.104 [C:\Program Files\dotnet\sdk]
  3.1.301 [C:\Program Files\dotnet\sdk]
  3.1.401 [C:\Program Files\dotnet\sdk]

.NET Core runtimes installed:
  Microsoft.AspNetCore.All 2.1.13 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.14 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.15 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.21 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.2.2 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.App 2.1.13 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.14 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.15 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.21 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.2.2 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.1.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.1.7 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 1.0.15 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 1.1.12 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.13 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.14 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.15 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.21 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.2.2 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.1.0 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.1.7 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.WindowsDesktop.App 3.1.0 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 3.1.7 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

我还尝试从开发人员命令提示符（VS2017和VS2019）构建项目，并且它不适用于VS2017（带有msbuild）。

我比较了两台机器（我和一台正在运行的机器）的VS2017 msbuild输出，发现以下差异：

VS2017（正在运行）

...
Resolving SDK 'Microsoft.NET.Sdk'...
Property reassignment: $(MSBuildAllProjects)=";C:\Program Files\dotnet\sdk\2.2.110\Sdks\Microsoft.NET.Sdk\Sdk\Sdk.props;C:\Test\...."

VS2017（不起作用）

...
Resolving SDK 'Microsoft.NET.Sdk'...
Property reassignment: $(MSBuildAllProjects)=";;C:\Program Files (x86)\Microsoft Visual Studio\2017\Enterprise\MSBuild\Sdks\Microsoft.NET.Sdk\Sdk\Sdk.props;;C:\Test\...."

msbuild如何确定“ c：\ program files \ dotnet \ sdk *”（在我的机器上为“ c：\ program files（x86）\ VS * \ sdk *”）的路径？

关于如何继续查找故障的任何想法？