In Visual Studio (not code) 2019 create an ASP.NET Core 3.1 Angular solution.
Notice that the package.json defaults to Angular 8.
Now run an NG Update (to attempt to get to Angular 9).
Once you are ready, start the project from Visual Studio (IIExpress).
There are many more 'legacy' things going on with Visual Studio regarding tools that are out of date, but I'll save that for another post.
An unhandled exception occurred while processing the request. AggregateException: One or more errors occurred. (One or more errors occurred. (The NPM script 'start' exited without indicating that the Angular CLI was listening for requests. The error output was: )) System.Threading.Tasks.Task.ThrowIfExceptional(bool includeTaskCanceledExceptions) InvalidOperationException: The NPM script 'start' exited without indicating that the Angular CLI was listening for requests. The error output was: Microsoft.AspNetCore.SpaServices.AngularCli.AngularCliMiddleware.StartAngularCliServerAsync(string sourcePath, string npmScriptName, ILogger logger)
Not to sing the blues, but the the entire new project npm install takes about 10 minutes. This is a long time when the day has already been uncooperative.
I didn't try all the solutions, but the "place echo in front of ng serve" did not work.