Unable to upload file

I’m executing this logic:

require_once( ABSPATH . ‘wp-admin/includes/file.php’ );
$uploadedfile = $_FILES[‘file’];
$upload_overrides = array( ‘test_form’ => false );
$movefile = wp_handle_upload( $uploadedfile, $upload_overrides );

But it seems that it’s not working as expected. The variable $uploadedfile is empty and I cannot move on.

Did anybody deal with this issue?