[wp-trac] [WordPress Trac] #64404: Uncaught DivisionByZeroError: Modulo by zero

[WordPress Trac]

#64404: Uncaught DivisionByZeroError: Modulo by zero
----------------------------+-----------------------------
 Reporter:  kaushiksomaiya  |      Owner:  (none)
     Type:  defect (bug)    |     Status:  new
 Priority:  normal          |  Milestone:  Awaiting Review
Component:  Cron API        |    Version:
 Severity:  normal          |   Keywords:
  Focuses:                  |
----------------------------+-----------------------------
 Hello team,

 It seems there's a possibility of plugins or custom code inadvertently
 inserting boolean value in custom schedule intervals. When that happens -
 Cron breaks badly even after removal of the custom code/plugin declaring
 it. This is because there's an attempt to reschedule the event before
 executing it.. and probably if ( 0 === $interval ) { doesn't evaluate true
 for the bool value.

 To Replicate:

 {{{
 // 1. Add a broken schedule
 add_filter( 'cron_schedules', function( $schedules ) {

     // INTENTIONALLY BROKEN
     $schedules['kscronbreaker_cron_schedule'] = array(
         'interval' => false,          // ❌ Wrong: must be integer > 0
         'display'  => 'Broken Cron Schedule',
     );

     return $schedules;
 } );

 // 2. Try to schedule the event
 add_action( 'init', function() {

     if ( ! wp_next_scheduled( 'kscronbreaker_broken_cron_hook' ) ) {
         wp_schedule_event(
             time() + 10,
             'kscronbreaker_cron_schedule',
             'kscronbreaker_broken_cron_hook'
         );
     }
 } );

 // 3. Cron handler (never runs)
 add_action( 'kscronbreaker_broken_cron_hook', function() {
     error_log( 'KS Cron Breaker executed — THIS SHOULD NEVER APPEAR' );
 } );
 }}}


 Then check the server's fatal error logs

 Uncaught DivisionByZeroError: Modulo by zero in /wp-5351423/wp-
 includes/cron.php:436

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Ticket URL: <https://core.trac.wordpress.org/ticket/64404>
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