Plugin breaks cron on multiple plugins

Hey Mark,

I cannot find a plugin called ‘WP-Cron Events’. Do you, by any chance, mean ‘WP Crontrol’?

I installed ‘WP Crontrol’ and it works flawless with my plugin.

I didn’t try the other plugin ‘WooZone Amazon Associates’ yet.

Do you also have problems if you don’t use the Optimize Database scheduler? Or only if you put it into the Cron?

peace,
Rolf

Hi Rolf,

Sorry about that, the plugin is called WP Crontrol. Issue occurs whether or not I have optimize database scheduler enabled. Maybe this is a conflict with another plugin I am using, I will re-test right now by disabling everything except wp crontrol and your plugin and let you know the results. Thanks for the quick followup. Talk soon.

Regards,
Mark

Hi Rolf,

Just set my site to default wordpress 2015 theme, disabled every plugin except your plugin and WP Crontrol. Still breaks things. Did you test by going to settings in dashboard, choosing cron schedules, and setting up a test cron? When your plugin is enabled, all test crons vanish from view, normally you can view and manage them by deleting with the x next to the custom cron events shown in the list. When I disable your plugin, the test crons show back up.

Mark

Hey Mark,

Thanks for the feedback!

Okay, so you add a new Cron entry by hand, using WP Crontrol.
and when my plugin is enabled, it doesn’t show.

Got it! I’ll try, see what happens and report back.

peace,
Rolf

Hey Mark,

Hummmmmm…
I manually scheduled a task from one of my other plugins (using WP Crontrol) and set it to run every five minutes (a schedule the Optimize Database plugin adds for testing purposes).

It runs nicely, every 5 minutes (with Optimize Database enabled).

So, I’m puzzled ??

peace,
Rolf

I’m puzzled as well. I haven’t had any issues with your plugin for years. The only thing difference with my new website is that InnoDB is the database default. Could that be a problem?

I’m having an issue as well with another plugin. WP Missed Schedule Fix Future Posts Failed is no longer working.

https://www.ads-software.com/plugins/wp-missed-schedule/

I look at the cron events or what’s in cron and the schedules it defined are not present and it’s event is not registered.

These are the Schedules available when I disable ODB.

Available schedules

Every Ten Minutes, every 10 mins
[W3TC] Object Cache file GC (every 3600 seconds), every 1 hour
[W3TC] Page Cache file GC (every 3600 seconds), every 1 hour
[W3TC] Page Cache prime (every 900 seconds), every 15 mins
[W3TC] CDN queue process (every 900 seconds), every 15 mins
[W3TC] CDN auto upload (every 3600 seconds), every 1 hour
[W3TC] Minify file GC (every 86400 seconds), every 1 day
Once Hourly, every 1 hour
Twice Daily, every 12 hours
Once Daily, every 1 day

When I enable the plugin, all of the custom schedules disappear, except for the ones the ODB plugin creates…

Available schedules

Once Weekly, every 1 week
Every Five Minutes, every 5 mins
Once Hourly, every 1 hour
Twice Daily, every 12 hours
Once Daily, every 1 day

So I believe this causes all of plugins that rely on a custom schedule to break.

Rich

I believe the code that registers the schedules is not correct.

From https://codex.www.ads-software.com/Plugin_API/Filter_Reference/cron_schedules

function my_add_weekly( $schedules ) {
	// add a 'weekly' schedule to the existing set
	$schedules['weekly'] = array(
		'interval' => 604800,
		'display' => __('Once Weekly')
	);
	return $schedules;
}
add_filter( 'cron_schedules', 'my_add_weekly' );

What is done in the plugin:

// ADD EXTRA CRON SCHEDULES
		add_filter('cron_schedules', array(&$this, 'odb_extra_cron_schedules'));

function odb_extra_cron_schedules()
	{
		global $odb_class;

		$schedules['weekly'] = array(
			'interval' => 604800,
			'display'  => __('Once Weekly', $odb_class->odb_txt_domain)
		);
		// FOR DEBUGGING
		$schedules['fiveminutes'] = array(
			'interval' => 300,
			'display'  => __('Every Five Minutes', $odb_class->odb_txt_domain)
		);
		return $schedules;
	} // odb_extra_cron_schedules()

The method is not taking in the passed in $schedules objects. It is creating its own.

I changed the line to

function odb_extra_cron_schedules($schedules)

And now all the custom schedules created by my other plugins W3TC, Missed Posts, etc. are now registered properly.

I still don’t see the event from missed posts showing up in the events list, so I will investigate further.

Update ***

I deactivated, then reactivated the WP Missed Schedule Fix Future Posts Failed plugin after applying my fix to this plugin and now the event is appearing properly.

Rich

Very interesting, thank you for sharing your findings Rich. I knew I wasn’t crazy as the same thing happens to me in that all the custom schedules disappear when Optimize Database after Deleting Revisions is enabled, and reappear when it is disabled. I don’t like to edit a plugin authors plugin for I believe they should be the ones fixing something broken but I will have to test out what you just put here for the author didn’t fine an issue himself.

Update:

Just added the $schedules value to the plugin file rvg-optimize-database/classes/odb-scheduler.php per Rich’s findings and now my custom cron jobs show up as intended. I’m waiting for my next cronjob to kick in automatically when the Woozone plugin updates at the next scheduled time before I can say with certainty my problem is fixed but so far it looks like it is.

Rich, thank you very much for finding this solution. I’m not sure if Rolf is still subscribed to this support thread but I hope he gets wind of your findings and digs a little deeper.

Best Regards,
Mark

This is a definite plugin bug which is simply fixed as per the details from Rich.

I think the plugin author maybe misunderstood the plugin bug and thought it was something to do with cron events not running rather than schedule interval definitions not being available.

The confusing thing with this particular plugin bug is that the effect can vary based on the order of plugin initialisation by WordPress since this determines the order in which filters adding additional schedule intervals are executed.

What should happen is that as each plugin filter runs it takes the existing schedules array passed as a parameter by WordPress and adds custom schedules to it and then returns the updated array.

What this plugin is currently doing is _not_ taking the existing array (which it should take as the parameter of the filter function call) but effectively defining a new schedules array, adding it’s own schedule definitions and then returning that new array.

The effect is that any filter function for other plugins that are executed _before_ this plugin filter function will have the schedules they have added discarded but any plugin filter functions that run _after_ this plugin filter will have their schedule definitions added to the new schedules array that this plugin created.

Apart from fixing the plugin code as Rich indicates the other workaround is to try and force this plugin to be the first plugin that WordPress initializes (loads) and so its filter will be executed first and hopefully you would then get the additional custom schedules from other plugins as their filters would run after that of this plugin. But this is _not_ a solution but just a workaround because the core WordPress schedules that WordPress populates into the original schedules array will still be lost.

@mark,

I found that I had to deactivate/reactivate or resave the settings of some of my plugins in order for the plugin to reapply its event, after I fixed the bug. If your event isn’t showing up try this.

Rich

Hey guys,

I fixed the Cron Schedule issue and released v4.0.3.

Thanks for all your feedback and testing!

peace,
Rolf

Rolf,

Thanks for the quick response!

Rich