ErrorException when using Laravel's elixir to import a CSS file

I'm following a Laracast tutorial, episode 6, and I reached the part where the instructor uses <link rel="stylesheet" href="{{ elixir('css/app.css') }}"/> too call the CSS file, but whenever I do this, the following error is thrown:

ErrorException in helpers.php line 341:

file_get_contents(/home/gabriel/Documents/Rxe/public/build/rev-manifest.json): failed to open stream: No such file or directory (View: /home/gabriel/Documents/Rxe/resources/views/admin/layout.blade.php) (View: /home/gabriel/Documents/Rxe/resources/views/admin/layout.blade.php)

I've followed everything from the beginning, but I'm stuck at it.

via Chebli Mohamed