React Error: Can't resolve module (not found) in React.js

Do you have the import line for your React module correct, but getting an error in console?

import App from "./components/App";

For me, I had the input correct but npm start can be buggy. If I move files to different folders, npm start doesn't pick up on these changes. I need to cancel npm start process, make the move, save and then run npm start and it will see the files now.

Not a problem! Except for all of my pulled out hair in the process...