save_deferred_events() Causes MySQL “Commands out of sync” Errors on Shutdown

[SaiPhanindraVutukuru]

Prerequisites

• I have carried out troubleshooting steps and I believe I have found a bug.
• I have searched for similar bugs in both open and closed issues and cannot find a duplicate.

Describe the bug

We’ve identified a critical issue in Pinterest for WooCommerce v1.4.21 that causes database corruption and cascading plugin failures.

Problem: The save_deferred_events() method recursively calls load_deferred_events() during WordPress shutdown. This triggers multiple unbuffered MySQL operations (get_transient, delete_transient, set_transient) while the DB connection is in a sensitive state, causing:

Commands out of sync; you can't run this command now errors

Corruption of MySQL connection during shutdown hooks

Cascade failures in other plugins (e.g., RankMath, Jetpack, WooCommerce batch processor)

Permalink issues and “Page not found” errors

Impact:

DB connection corruption affects all shutdown hooks.

Cascading failures in other WooCommerce and SEO plugins.

Rapid error log growth and potential site-wide issues.

Expected behavior

save_deferred_events() should not corrupt MySQL connections during shutdown.

Plugin operations should gracefully handle deferred events without recursive DB calls

Actual behavior

When Pinterest for WooCommerce is active, the save_deferred_events() method recursively calls load_deferred_events() during WordPress shutdown, triggering multiple unbuffered MySQL operations. This causes:

Commands out of sync; you can't run this command now errors in the logs

MySQL connection corruption during shutdown hooks

Cascade failures in other plugins (RankMath, Jetpack, WooCommerce batch processor)

Permalink issues and “Page not found” errors for all pages except the homepage

Disabling the plugin or blocking its scheduled actions stops the errors, confirming the plugin is the root cause.

Steps to reproduce

Install Pinterest for WooCommerce v1.4.21 on a WooCommerce site.

Enable the plugin and allow scheduled actions to run (or trigger via page load).

Observe Commands out of sync errors in logs during shutdown.

Optional:

Disable Pinterest plugin → errors stop

Block Pinterest scheduled actions → errors stop

Reactivate plugin → errors return

WordPress Environment

System Status Report

### WordPress Environment ###

WordPress address (URL): [Redacted]
Site address (URL): [Redacted]
WC Version: 10.1.2
Legacy REST API Package Version: The Legacy REST API plugin is not installed on this site.
Action Scheduler Version: ✔ 3.9.3
Log Directory Writable: ✔
WP Version: 6.8.2
WP Multisite: –
WP Memory Limit: 6 GB
WP Debug Mode: –
WP Cron: ✔
Language: en_US
External object cache: ✔

### Server Environment ###

Server Info: LiteSpeed
Server Architecture: Linux 5.14.0-503.38.1.el9_5.x86_64 x86_64
PHP Version: 8.2.28
PHP Post Max Size: 6 GB
PHP Time Limit: 480
PHP Max Input Vars: 5000
cURL Version: 7.76.1
OpenSSL/3.2.2

SUHOSIN Installed: –
MySQL Version: 11.8.3-MariaDB-log
Max Upload Size: 6 GB
Default Timezone is UTC: ✔
fsockopen/cURL: ✔
SoapClient: ✔
DOMDocument: ✔
GZip: ✔
Multibyte String: ✔
Remote Post: ✔
Remote Get: ✔

### Database ###

[REDACTED]

### Post Type Counts ###

acf-field: 4
acf-field-group: 3
afreg_fields: 1
attachment: 2120
b2bking_custom_field: 4
b2bking_custom_role: 2
b2bking_group: 2
b2bking_list: 1
b2bking_rule: 3
clients: 4
custom_css: 4
customize_changeset: 6
def_reg_fields: 10
elementor_library: 34
igmap: 1
is_search_form: 1
mc4wp-form: 1
nav_menu_item: 69
page: 18
post: 5
prl_engine: 1
product: 342
product_variation: 1619
rank_math_schema: 19
revision: 28
rm_content_editor: 1
seedprod: 2
shop_order: 1562
shop_order_refund: 1
shop-the-look: 14
shopengine-template: 3
stores: 4
team: 5
testimonials: 6
um_directory: 2
um_form: 7
user_registration: 1
wc_conditional_fee: 1
wcs_ruleset: 1
wp_global_styles: 1

### Security ###

Secure connection (HTTPS): ✔
Hide errors from visitors: ✔

### Active Plugins (46) ###

WPA Module: by WPaccess – 1.0
Advanced Custom Fields: by WP Engine – 6.5.1
All-in-One WP Migration and Backup: by ServMask – 7.99
B2BKing Core: by WebWizards – 4.9.10
B2BKing Pro: by WebWizards – 5.4.00
Classic Widgets: by WordPress Contributors – 0.3
Code Snippets: by Code Snippets Pro – 3.7.0
Elementor: by Elementor.com – 3.32.1
Envato Market: by Envato – 2.0.12
Finix for WooCommerce: by Finix – 1.2.0
Flexible Shipping: by Octolize – 6.4.0
Import and export users and customers: by codection – 1.29.5
Smash Balloon Instagram Feed: by Smash Balloon – 6.9.1
Interactive Geo Maps PRO: by Carlos Moreira – 1.5.6
Intuitive Custom Post Order: by hijiri – 3.2.0
Kadence WooCommerce Email Designer: by Kadence WP – 1.5.17
LiteSpeed Cache: by LiteSpeed Technologies – 7.5.0.1
Manage Notification E-mails: by Virgial Berveling – 1.8.6
Smart Slider 3 Pro: by Nextend – 3.5.1.29
Omnisend for WooCommerce: by Omnisend – 1.16.9
Newsletters, Email Marketing, SMS and Popups by Omnisend: by Omnisend – 1.7.7
Pinterest for WooCommerce: by WooCommerce – 1.4.21
Qi Addons for Elementor: by Qode Interactive – 1.9.3
Qode Framework: by Qode Interactive – 1.2.6
Really Simple Security: by Really Simple Security – 9.5.0.2
Search By SKU - for Woocommerce: by Unroll Digital – 0.8.0
Search Exclude: by QuadLayers – 2.5.6
Rank Math SEO PRO: by Rank Math SEO – 3.0.96
Rank Math SEO: by Rank Math SEO – 1.0.253
Shop The Look: by  –
Sirv: by sirv.com – 8.0.2
MoreConvert Wishlist for WooCommerce: by MoreConvert – 1.9.8
Zoho ZeptoMail: by Zoho Mail – 3.2.9
Umea Core: by Qode Interactive – 1.3
User Role Editor: by Vladimir Garagulya – 4.64.5
WooCommerce Gateway Affirm: by WooCommerce – 3.0.3
WooCommerce Product Recommendations: by WooCommerce – 2.3.0
WooCommerce: by Automattic – 10.1.2
Wordfence Security: by Wordfence – 8.1.0
WP Crontrol: by John Blackbourn – 1.19.2
WP Rollback: by WP Rollback – 3.0.7
WP Widget in Navigation: by Yudiz Solutions Ltd. – 3.1
WPFront Notification Bar: by Syam Mohan – 3.5.1
XT Variation Swatches for WooCommerce Pro: by XplodedThemes – 1.9.7
Zoho CRM WordPress Integration: by WPAccess – 1.0.0
Zoho SalesIQ: by Zoho SalesIQ Team – 2.0.4

### Inactive Plugins (2) ###

Disable Emails: by WebAware – 1.8.2
WP Activity Log: by Melapress – 5.5.1

### Dropin Plugins () ###

object-cache.php: LiteSpeed Cache - Object Cache (Drop-in)

### Settings ###

Legacy API Enabled: –
Force SSL: –
Currency: USD ($)
Currency Position: left
Thousand Separator: ,
Decimal Separator: .
Number of Decimals: 2
Taxonomies: Product Types: external (external)
grouped (grouped)
simple (simple)
subscription (subscription)
variable (variable)
variable subscription (variable-subscription)

Taxonomies: Product Visibility: exclude-from-catalog (exclude-from-catalog)
exclude-from-search (exclude-from-search)
featured (featured)
outofstock (outofstock)
rated-1 (rated-1)
rated-2 (rated-2)
rated-3 (rated-3)
rated-4 (rated-4)
rated-5 (rated-5)

Connected to WooCommerce.com: –
Enforce Approved Product Download Directories: –
HPOS feature enabled: –
Order datastore: WC_Order_Data_Store_CPT
HPOS data sync enabled: –
Enabled Features: analytics
marketplace
order_attribution
site_visibility_badge
remote_logging
blueprint
point_of_sale


### Logging ###

Enabled: ✔
Handler: Automattic\WooCommerce\Internal\Admin\Logging\LogHandlerFileV2
Retention period: 30 days
Level threshold: –
Log directory size: 297 MB

### WC Pages ###

Shop base: woocommerce/woocommerce#34578 - /shop/
Cart: woocommerce/woocommerce#4604 - /cart/ -  Contains the [woocommerce_cart] shortcode
Checkout: woocommerce/woocommerce#22606 - /checkout/ -  Contains the [woocommerce_checkout] shortcode
My account: woocommerce/woocommerce#16092 - /my-account/ -  Contains the [woocommerce_my_account] shortcode
Terms and conditions: ❌ Page not set

### Theme ###

Name: Umea Child
Version: 1.0.0
Author URL: https://qodeinteractive.com
Child Theme: ✔
Parent Theme Name: Umea
Parent Theme Version: 1.6
Parent Theme Author URL: https://qodeinteractive.com
Theme type: Classic theme
WooCommerce Support: ✔

### Templates ###

Overrides: umea-child/woocommerce/cart/cart.php version 7.9.0 is out of date. The core version is 10.1.0
umea-child/woocommerce/emails/admin-new-order.php version 3.7.0 is out of date. The core version is 10.0.0
umea-child/woocommerce/emails/customer-completed-order.php version 3.7.0 is out of date. The core version is 9.9.0
umea-child/woocommerce/emails/email-addresses.php version 5.6.0 is out of date. The core version is 9.8.0
umea/inc/woocommerce/templates/global/quantity-input.php version 7.4.0 is out of date. The core version is 10.1.0
umea-child/woocommerce/myaccount/dashboard.php version - is out of date. The core version is 4.4.0
umea-child/woocommerce/myaccount/form-edit-account.php version - is out of date. The core version is 9.7.0
umea-child/woocommerce/myaccount/form-edit-address.php
umea-child/woocommerce/myaccount/form-login.php version - is out of date. The core version is 9.9.0
umea-child/woocommerce/myaccount/form-lost-password.php
umea-child/woocommerce/myaccount/my-address.php version - is out of date. The core version is 9.3.0
umea-child/woocommerce/myaccount/orders.php
umea/inc/woocommerce/templates/single-product/meta.php version 3.0.0 is out of date. The core version is 9.7.0
/home/u802451898/domains/orchidsluxhome.com/public_html/partners/wp-content/plugins/sirv/plugdata/woo_templates/woo-product-template.php

Outdated Templates: ❌
					
					
						Learn how to update					 |
					
						
					
					
						Clear system status theme info cache

### Admin ###

Enabled Features: activity-panels
analytics
product-block-editor
coupons
core-profiler
customize-store
customer-effort-score-tracks
import-products-task
experimental-fashion-sample-products
shipping-smart-defaults
shipping-setting-tour
homescreen
marketing
mobile-app-banner
onboarding
onboarding-tasks
pattern-toolkit-full-composability
product-custom-fields
remote-inbox-notifications
remote-free-extensions
payment-gateway-suggestions
printful
shipping-label-banner
subscriptions
store-alerts
transient-notices
woo-mobile-welcome
wc-pay-promotion
wc-pay-welcome-page
launch-your-store
add-to-cart-with-options-stepper-layout

Disabled Features: product-data-views
experimental-blocks
experimental-iapi-mini-cart
experimental-iapi-runtime
coming-soon-newsletter-template
minified-js
product-pre-publish-modal
settings
async-product-editor-category-field
product-editor-template-system
use-wp-horizon
experimental-wc-rest-api

Daily Cron: ✔ Next scheduled: 2025-09-19 05:12:59 -05:00
Options: ✔
Notes: 52
Onboarding: completed

### Action Scheduler ###

Canceled: 2,792
Oldest: 2025-08-19 06:10:12 +0000
Newest: -0001-11-30 00:00:00 +0000

Complete: 49,448
Oldest: 2025-08-18 23:08:36 +0000
Newest: 2025-09-18 10:17:31 +0000

Failed: 231
Oldest: 2023-05-04 09:17:09 +0000
Newest: 2025-08-27 09:17:58 +0000

In-progress: 1
Oldest: –
Newest: –

Pending: 18
Oldest: 2025-09-18 10:27:29 +0000
Newest: 2025-10-17 00:23:57 +0000


### Product Recommendations ###

Database Version: 2.3.0
Loopback Test: ✔
Task Queueing Test: ✔
Page Cache Test: ❌ Test failed.

### Status report information ###

Generated at: 2025-09-18 05:17:31 -05:00

Isolating the problem

• I have deactivated other plugins and confirmed this bug occurs when only WooCommerce plugin is active.
• This bug happens with a default WordPress theme active, or Storefront.
• I can reproduce this bug consistently using the steps above.

[WPAccess]

Additional Details and Proposed Fix from My Testing

I wanted to provide more detailed findings from my testing regarding the Pinterest for WooCommerce v1.4.21 issue.

What I Found:

• The problem is in the save_deferred_events() method in /src/Tracking/Tag.php.
• It calls load_deferred_events() recursively during WordPress shutdown.
• This triggers multiple database operations (get_transient(), delete_transient(), set_transient()) in a sensitive state, causing "Commands out of sync" errors and corrupting the MySQL connection.
• Other plugins like RankMath, Jetpack, and WooCommerce batch processor also start failing due to this corrupted connection.
• Permalink issues and “Page not found” errors appear on all pages except the homepage.

Steps I Tested:

1. Disabled Pinterest plugin → All related errors stopped
2. Re-activated Pinterest plugin → Errors returned immediately
3. Blocked Pinterest scheduled actions → Errors stopped
4. Unblocked scheduled actions → Errors returned

Impact Observed:

• Database connection corruption during every shutdown
• Cascade failures in other WooCommerce/SEO plugins
• Rapid growth of error logs
• Temporary permalink issues

Proposed Fix (Currently in Testing Phase):
I refactored the save_deferred_events() method to remove the recursive call to load_deferred_events(). This keeps the functionality intact while preventing MySQL corruption.

public static function save_deferred_events() {
    $transient_key = static::get_deferred_events_transient_key();
    if ( ! $transient_key || empty( static::$deferred_events ) ) {
        return;
    }

    // Get existing events directly without recursive call
    $existing_events = get_transient( $transient_key );
    if ( false === $existing_events ) {
        $existing_events = array();
    }

    $all_events = array_merge( $existing_events, static::$deferred_events );
    set_transient( $transient_key, $all_events, DAY_IN_SECONDS );
}

This proposed fix is currently in the testing phase on my staging environment.

[nerrad]

Hi there, this repository is for WooCommerce, not Pinterest for WooCommerce.