Does the 'init' hook works for all sites in multisite?

Question

Im trying to trigger a configuration everytime I create a new subsite on multisite environment, like so:

add_action('init', 'mgh_set_events_option', 99); 
function mgh_set_events_option(){
  $mgh_is_set_options = get_option('mgh_is_set_options');
    if(!$mgh_is_set_options){
        print_r('setting options');
        update_option( 'mgh_is_set_options', true );
    }
}

The problem is that the 'init' action does not trigger in some sites from our multisite instance. There is any principle of why this happens?

Answer 1

If your code is in a theme's functions.php, it'll only run on sites where that theme is active. You can ensure that it's active on all your sites by putting that code snippet into a plugin that's active on every site (ie, Network Activated). Alternately, you can use a Must-Use plugin to ensure that it runs on every site in your Multisite network.

Answer 2

The init hook will run whenever WordPress is loaded. So if you have a plugin or theme that uses the init hook activated on multiple sites it will work on all sites that the plugin or theme is active on.

However, the hook will only run for the site that is loaded. If you load a page on Site A your callback will run and update the option on Site A, but it will not update the option on Site B until a page on Site B is loaded and the hook is run for that site.