Custom Post Type 404 Error even after flushing rewrite rules

Question

I've declared a custom post type as below, I can create posts in admin but when I try to view I'm getting 404 error. I've declared a previous custom post type using similar code and it worked fine. I don't want an archive page, but do want single post pages.

I've tried flushing the rewrite rules, and deactivating plugins but neither has worked. Any help would be greatly appreciated!!

//create courses post type
add_action( 'init', 'create_courses_post_type' );
function create_courses_post_type() {
    $labels = array(
        'name'               => __( 'Courses' ),
        'singular_name'      => __( 'Course' ),
        'all_items'          => __( 'All Courses' ),
        'add_new'            => _x( 'Add New Course', 'Courses' ),
        'add_new_item'       => __( 'Add New Course' ),
        'edit_item'          => __( 'Edit Course' ),
        'new_item'           => __( 'New Course' ),
        'view_item'          => __( 'View Course' ),
        'search_items'       => __( 'Search in Courses' ),
        'not_found'          => __( 'No Courses found' ),
        'not_found_in_trash' => __( 'No Courses found in trash' ),
        'parent_item_colon'  => ''
    );
    $args = array(
        'labels'             => $labels,
        'public'             => true,
        'has_archive'        => false, // Set to false hides Archive Pages
        'menu_icon'          => 'dashicons-welcome-learn-more', //pick one here ~> https://developer.wordpress.org/resource/dashicons/
        'rewrite'            => array( 'slug' => 'courses' ),
        'taxonomies'         => array( 'category', 'post_tag' ),
        'query_var'          => true,
        'menu_position'      => 9,
        'publicly_queryable' => true
    );
    register_post_type( 'course', $args );
}

Answer 1

Your code is working perfectly. You have to refresh/flush permalinks after creating "Custom Post Type" hook.

Step 1: In the main menu find "Settings > Permalinks".
Step 2: Scroll down if needed and click "Save Changes".
Step 3: Rewrite rules and permalinks are flushed.