Fixing “Invalid Product” Errors from Upsell Plugin Conflicts in WooCommerce

Issue Overview

A WooCommerce store saw sitewide cart failures after a plugin update. Users couldn’t add any product to their cart—each attempt triggered an “Invalid product” error. This occurred despite no changes to product settings.

What We Found

🚨 JavaScript conflicts

DevTools showed errors tied to modal popups triggered by the “Add to Cart” button.

🔍 Plugin interference

The issue traced back to two plugins:

• WooCommerce Upsell Popup

• WooCommerce Upsell Popup PRO

🔄 Staging validation

Disabling these plugins restored normal cart behavior instantly.

How We Fixed It

✅ Disabled upsell plugins

Both upsell extensions were turned off to restore cart functionality across the site.

✅ Communication

Clients were informed that upsell features were temporarily disabled to allow seamless purchases.

✅ Isolated the root cause

The plugin tried loading a removed upsell product, blocking the entire cart flow.

✅ Planned next steps

Options included updating or replacing the plugin—or adjusting settings to avoid similar future conflicts.

Result

Cart and checkout functionality was fully restored within hours. Sales resumed, and a safe path was created for upsell reactivation or alternative solutions.

Experiencing errors with WooCommerce add-to-cart or upsell plugins?

Integriti Studio can help you troubleshoot and resolve plugin conflicts without compromising your sales.

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