Display Custom Error Message When ICS URL Is Unavailable (404 Error)

At present there is not a way to do this. However I don’t think it would be a good idea to add it as an option. If the source feed URL is invalid, it will never display any events, so the site admin who is setting it up should realize there’s a problem and fix the URL. There is currently a PHP error message that displays when the feed URL is invalid, and consistent with standard PHP rules it only displays if the display_errors PHP option is enabled.

thanks for your answer,

what do you thinks about this solution :

function custom_ics_calendar_shortcode($atts) {

    $a = shortcode_atts( array(
        'url' => '',
        'title' => 'true',
        'view' => 'month',
        'maskinfo' => '',
        'showendtimes' => 'false',
        'format' => 'j F'
    ), $atts );


    $response = wp_remote_head( $a['url'] );
    
    if ( is_wp_error( $response ) || wp_remote_retrieve_response_code( $response ) != 200 ) {

        return '<p>No dates available</p>';
    } else {

        $shortcode = '[ics_calendar url="' . esc_url($a['url']) . '"'
            . ' title="' . esc_attr($a['title']) . '"'
            . ' view="' . esc_attr($a['view']) . '"'
            . ' maskinfo="' . esc_attr($a['maskinfo']) . '"'
            . ' showendtimes="' . esc_attr($a['showendtimes']) . '"'
            . ' format="' . esc_attr($a['format']) . '"]';

        return do_shortcode($shortcode);
    }
}

add_shortcode('custom_ics_calendar', 'custom_ics_calendar_shortcode');

That seems relevant to me, but am I perhaps missing something?

That seems like it would work, but it may not be very efficient because it will force the feed URL to be retrieved multiple times (or at least once per page load even when ICS Calendar has the feed cached).

I’m curious as to why you want to have this message display, since it’s only going to occur when there’s an error with your source feed. It would be best to fix the feed.