1> 微软官方.NET Core SDK以及Runtime下载 : https://dotnet.microsoft.com/download/archives
下载时注意有x86 和x64 版本区别
2> .net 2.2 loast afte upgrading to 15.9.2
"Use previews of the .NET Core SDK" option under menu -> Tools -> Options -> Projects and Solutions -> .NET Core
3>The current .NET SDK does not support targeting .NET Core 2.2. Either target .NET Core 2.1 or lower, or use a version of the .NET SDK that supports .NET Core 2.2.
是因为没有安装x86的SDK (.NET Core 2.2 )，安装好之后就ok了. 至于为什么在64位的电脑上安装32位的SDK才能正确我真不知道，再去研究下看看
原文：https://www.cnblogs.com/wplee/p/10368143.html