Wordpress cron is running with previously set time intervals and not the updated one

Question

For testing purposes I keep short time intervals for cron and when the functionality is working fine, I change it to the required time interval. Whenever I change the time intervals for ex: from 'three_days' to 'five_minutes' or from 'five_minutes' to 'fifteen_minutes', the cron is running with earlier frequency and not the updated one. I'm totally confused with this. Even after setting new intervals, cron function runs on previous time intervals only.

What might be the reason for this, kindly help me out on this.

This is my code:

add_filter('cron_schedules', 'filter_cron_schedules');
function filter_cron_schedules($schedules) {
    $schedules['fifteen_minutes'] = array(
        'interval' => 900, // seconds
        'display'  => __('Every 15 minutes') 
    );
    $schedules['twenty_minutes'] = array(
        'interval' => 1200, // seconds
        'display'  => __('Every 20 minutes') 
    );
    $schedules['three_days'] = array(
        'interval' => 259200, // seconds
        'display'  => __('Every 3 days') 
    );
    $schedules['five_minutes'] = array(
        'interval' => 300, // seconds
        'display'  => __('Every 5 minutes') 
    );
    return $schedules;
}
// Schedule the cron
add_action('wp', 'bd_cron_activation');
function bd_cron_activation() {
    if (!wp_next_scheduled('bd_cron_cache')) {
        wp_schedule_event(time(), 'twenty_minutes', 'bd_cron_cache'); // hourly, daily, twicedaily
    }
}
// Firing the function
add_action('bd_cron_cache', 'bd_data');
function bd_data() {
    // My Logic
}

Answer 1

Whenever I change the time intervals for ex: from 'three_days' to 'five_minutes' or from 'five_minutes' to 'fifteen_minutes', the cron is running with earlier frequency and not the updated one.

Because you only reschedule the event if it does not exist:

if ( ! wp_next_scheduled( 'bd_cron_cache' ) ) {
    // schedule
}

...which will always be false once you initially schedule the event. Instead, check the stored task's schedule against the value you actually want it to be:

if ( wp_get_schedule( 'bd_cron_cache' ) !== 'twenty_minutes' ) {
    // Above statement will also be true if NO schedule exists, so here we check and unschedule if required
    if ( $time = wp_next_schedule( 'bd_cron_cache' ) ) {
        wp_unschedule_event( $time, 'bd_cron_cache' );
    }
    wp_schedule_event( time(), 'bd_cron_cache', 'twenty_minutes' );
}

Answer 2

// Custom Cron Schedules
add_filter('cron_schedules', 'filter_cron_schedules');
function filter_cron_schedules($schedules) {
    $schedules['two_minutes'] = array(
        'interval' => 120, // seconds
        'display'  => __('Every 2 minutes') 
    );
    $schedules['twenty_minutes'] = array(
        'interval' => 1200, // seconds
        'display'  => __('Every 20 minutes') 
    );
    return $schedules;
}

// Schedule the cron
add_action('wp', 'bd_cron_activation');
function bd_cron_activation() {
    if ( wp_get_schedule('bd_cron_cache') !== 'two_minutes' ) {
            // Above statement will also be true if NO schedule exists, so here we check and unschedule if required
            if ( $time = wp_next_scheduled('bd_cron_cache'))
                wp_unschedule_event($time, 'bd_cron_cache');

            wp_schedule_event(time(),'two_minutes','bd_cron_cache');   
        }
}

// Firing the function
add_action('bd_cron_cache', 'bd_data');
function bd_data() {
    // My Logic
}