Bug Report: DivisionByZeroError in OrderStatus.php line 287

Summary

Plugin: WooCommerce Mercado Pago
Affected versions: v8.7.5, v8.7.8 (confirmed), possibly earlier versions
Severity: High
Impact: Webhook processing fails, preventing WooCommerce order notification emails from being sent
Frequency: Intermittent (affects approximately 10-15% of orders in our production environment)

Description

The plugin throws a fatal DivisionByZeroError when processing webhooks/notifications. This error causes the webhook processing script to terminate prematurely, which prevents WooCommerce from completing the order lifecycle and triggering notification emails to customers and administrators.

Key observations:

• Orders are created successfully in WooCommerce
• Payment is processed correctly by Mercado Pago
• Order metadata including _payment_method is saved correctly
• The error occurs during webhook/notification processing after order creation
• Affected orders do NOT send “New Order” emails to admin or customers

Error Details Error Message

PHP Fatal error: Uncaught DivisionByZeroError: Division by zero
File: /wp-content/plugins/woocommerce-mercadopago/src/Order/OrderStatus.php
Line: 287

Stack Trace

Stack trace:
#0 [internal function]: MercadoPago\Woocommerce\Order\OrderStatus->processRefundNotification()
#1 /wp-includes/class-wp-hook.php(324): call_user_func_array()
#2 /wp-includes/class-wp-hook.php(348): WP_Hook->apply_filters()
#3 /wp-includes/plugin.php(565): WP_Hook->do_action()

Production Evidence Error Occurrence Timeline

Production error logs show 22 occurrences of this error in January 2025: Date Time (UTC) Occurrences January 8, 2025 23:01:41 1 January 16, 2025 23:12:52 1 January 17, 2025 20:05 – 21:00 Multiple (8-10) January 18, 2025 03:05:33 1 January 20, 2025 03:10:52 1 January 24, 2025 03:15:55 1 Affected Orders

We identified 10 specific orders affected by this issue: Internal ID Order Date Payment Status Email Sent Notes 19643 Jan 12, 2025 Completed NO First reported case 19644 Jan 12, 2025 Completed NO 19645 Jan 12, 2025 Completed NO 19646 Jan 13, 2025 Completed NO 19688 Jan 15, 2025 Completed NO 19689 Jan 15, 2025 Completed NO 19699 Jan 16, 2025 Completed NO 19747 Jan 18, 2025 Completed NO 19772 Jan 20, 2025 Completed NO 19887 Jan 24, 2025 Completed NO Most recent case

Common characteristics:

• All orders used Mercado Pago as payment method
• All orders were successfully created and paid
• All orders have correct _payment_method metadata
• None triggered “New Order” email notifications
• Dates correlate with error log timestamps

Environment Information

WordPress: 6.9
WooCommerce: 10.4.3
PHP: 8.2.29
Theme: Bricks Child Theme 1.1
Server: Production environment (Ubuntu/Nginx)

Active payment plugins:

• WooCommerce Mercado Pago v8.7.5 → v8.7.8 (updated during investigation)

Reproduction Conditions

Based on our analysis, the error occurs when:

1. An order is created with Mercado Pago payment method
2. The order meta CURRENCY_RATIO (accessed via OrderMetadata::CURRENCY_RATIO) has certain values
3. A webhook/notification from Mercado Pago is processed
4. The webhook processing reaches line 287 where a division operation is performed

Critical observation:
The error appears to be related to the handling of the CURRENCY_RATIO order metadata, specifically at line 287 of OrderStatus.php where a division operation is performed during refund notification processing. Impact Analysis User Experience Impact

• Customers complete purchases successfully
• Customers do NOT receive order confirmation emails
• Store administrators do NOT receive new order notifications
• Orders must be manually reviewed to send confirmations

Business Impact

• Customer satisfaction affected (no confirmation emails)
• Increased support workload (customers inquire about orders)
• Manual intervention required for each affected order
• Potential loss of trust in checkout process

Technical Impact

• Fatal error terminates webhook processing
• WooCommerce order lifecycle interrupted
• Order status change hooks not triggered
• Email notification system bypassed

Additional Context Why This Affects Only Some Orders

The error appears to be intermittent because it depends on the state of CURRENCY_RATIO metadata for each specific order. In our environment, approximately 10-15% of Mercado Pago orders are affected. Version Comparison

We compared versions:

• v8.7.5: Error present at line 287
• v8.7.8: Error still present at line 287 (unchanged)
• Both versions have identical OrderStatus.php (626 lines)

The issue persists across version updates, suggesting it has not yet been addressed. Diagnostic Data Order Metadata Analysis

Affected orders show the following metadata patterns:

_payment_method: woo-mercado-pago-custom (present)
_payment_method_title: Mercado Pago (present)
_mp_currency_ratio: [varies across affected orders]
_mercadopago_payment_id: [present with valid IDs]
_order_stock_reduced: yes (stock was reduced correctly)
_new_order_email_sent: [absent - email was never sent]

Complete Error Log Entry Example

[24-Jan-2025 03:15:55 UTC] PHP Fatal error:  Uncaught DivisionByZeroError: Division by zero in /wp-content/plugins/woocommerce-mercadopago/src/Order/OrderStatus.php:287
Stack trace:
#0 [internal function]: MercadoPago\Woocommerce\Order\OrderStatus->processRefundNotification()
#1 /wp-includes/class-wp-hook.php(324): call_user_func_array()
#2 /wp-includes/class-wp-hook.php(348): WP_Hook->apply_filters()
#3 /wp-includes/plugin.php(565): WP_Hook->do_action()
#4 /wp-content/plugins/woocommerce-mercadopago/src/Notification/WebhookHandler.php: do_action()

Workaround Currently Applied

We have NOT modified the plugin code in production. Affected orders receive manual email notifications through WooCommerce admin panel (“Resend order emails” feature). Questions for Plugin Developers

1. Under what conditions should CURRENCY_RATIO metadata have values that could cause division by zero?
2. Is there a known scenario where this metadata is not properly initialized?
3. Are there configuration settings in the Mercado Pago plugin that might affect CURRENCY_RATIO values?
4. Has this issue been reported by other users?
5. Is line 287 in OrderStatus.php expected to handle edge cases for CURRENCY_RATIO?

Additional Information Available

We can provide:

• Complete error logs (sanitized)
• Database exports of affected order metadata (sanitized)
• Detailed webhook payloads if accessible
• Screen recordings of the issue occurring
• Direct access to staging environment for testing

Contact Information

Reporter: Roberto Garcés
Company: XpartanSys SRL
Email: [email protected]
Timezone: UTC-3 (Uruguay)
Preferred contact method: GitHub issue / Email

We are available to provide additional diagnostic information or testing access as needed.