Configuration.GetSection always returns null

Question

Every time I call Configuration.GetSection, the Value property of the returned object is always null.

My Startup constructor

Answer 1

var serviceProvider = services.BuildServiceProvider();

must come after all services.Configure calls.

Answer 2

In my case for Web Api Core 2.1, I needed Program.cs in the project root folder (the same folder as Startup.cs).

Answer 3

If all the other answers do not fix the problem, another reason could be that the properties of the Options class are private (or do not have accessible setters).