I am trying to switch a .netcore3.1 api back to .netcore2.1 so that I can experiment for another question
I edited the project file to change the TargetFramework to netcoreapp2.1
I can now see Microsoft.NETCore.App ( 2.1.0) in the SDK section of the Dependencies I expected to also see Microsoft.AspNetCore.App (2.1.1) there since I have that in another project with TargetFramework netcoreapp2.1
However it was missing so I tried to install it with Nuget.
Now I have Microsoft.AspNetCore.App showing under Packages
I wound up realizing it was better to start a new project from scratch using the new project Wizard.
There were just too many changes.
I did notice that my netcore3.1 project does not have a SDK folder