errorlog filling up with unserialize(): Error at offset

Action Scheduler is a library built by WooCommerce (i.e. WordPress, since they own WooCommerce) for the WooCommerce plugin to manage job queues more efficiently (i.e. sending customer emails, processing payments, etc.).

The Action Scheduler library is built in such a way to allow other plugins to include and use it. Notable plugins that also use the Action Scheduler library are RankMath, WPForms, WP Mail SMTP, The Events Calendar, WP Rocket, All in One SEO, Jetpack, Yoast SEO, MonsterInsights, Site Reviews, and many more.

Is there any chance that you attempted to manually modify any of the action scheduler entries in the database (i.e. in the wp_actionscheduler_actions table)? If so, that may be causing the problem (based on this issue in Github).

Regardless, here is how to fix it:

If you have access to WP-CLI and are familiar with how to to use it on your server, then this command should remove all actions (including any invalid entries) from the database:

wp action-scheduler clean

Otherwise, try following the directions in this post: https://www.mrkwp.com/2023/09/how-to-clear-scheduled-action-logs-in-wordpress/

Because I don’t think it is normal that a plugin like Site Reviews should cause the event logs to fill up with GB’s of lines within a few days.

You are correct, this is not normal so something else is going on.

I suppose it’s possible that there is a problem with the custom Site Reviews database tables. Site Reviews will schedule a plugin migration whenever it’s needed using Action Scheduler, so perhaps it is related to that?

You can check if this is the case like this:

Since you said you are familiar with deleting rows in the database, I am assuming you are also able to view the table rows. If so, view the wp_actionscheduler_actions table in your database and look under the “hook” column. Do all of the entries start with site-reviews/, or are they something else? And if so, what does the status say, complete, pending, or failed?

If most of the hook entries do not start with site-reviews/, then it’s likely that the problem is not directly coming from Site Reviews.

Here’s why:

The way Action Scheduler works is that the latest version of the library is always the one that is loaded. So if you have three different plugins that include Action Scheduler and each plugin has a different version of the library, only the one that has the latest version of the Action Scheduler library is the one that will be loaded and used by all three plugins.

Have you manually modified or deleted any tables in your database?

The error you provided shows this:

[25-Jul-2025 09:57:43 UTC] PHP Warning: unserialize(): Error at offset 214 of 284 bytes in /home/backgroun/public_html/wp-content/plugins/site-reviews/vendors/woocommerce/action-scheduler/classes/data-stores/ActionScheduler_DBStore.php on line 397 

This means that Action Scheduler is throwing an error when getting a queued action from the database and attempting to unserialize the data in the schedule column of the wp_scheduledactions_actions table in your database.

So to troubleshoot why this is happening, view the wp_scheduledactions_actions table in your database and look at the values in the schedule column. They should all have serialized values that look something like this:

Or more specifically, like this:

O:32:"ActionScheduler_IntervalSchedule":5:{s:22:"*scheduled_timestamp";i:1754012982;s:18:"*first_timestamp";i:1753926517;s:13:"*recurrence";i:86400;s:49:"ActionScheduler_IntervalSchedulestart_timestamp";i:1754012982;s:53:"ActionScheduler_IntervalScheduleinterval_in_seconds";i:86400;}

If there are any rows where the schedule value is empty or not a serialized string, then that entry is causing Action Scheduler to throw the PHP error that is filling up your log files.