This post shows you how to solve ASP.NET Core Scaffolding does not work in Visual Studio.
There was an error running the selected code generator:
'Unhandled Exception: System.IO.FileNotFoundException: Could not load file or assembly 'Microsoft.VisualStudio.Web.CodeGeneration.Utils, Version=18.104.22.168, Culture=neutral, PublicKeyToken=adb9793829ddae60'. The system cannot find the file specified. at Microsoft.VisualStudio.Web.CodeGeneration.Design.Program.Main(String args)'
To solve the problem, you can right click on your project, then select Manage Nuget Packages.
Next, Search Microsoft.VisualStudio.Web.CodeGeneratio.Utils, then install it.
If you can't install, You should install the missing libraries notified by Visual Studio.
Right click on your project, then select Properties.
Next, Select Application tab, then change your target framework to new version.
Note that the library version used must be similar to the target framework you have chosen.