Table of Contents
Problem Description #
When customers try to checkout with the plugin enabled, the site throws a fatal error (e.g. “Cannot use string offset as an array”), preventing checkout or breaking the order flow.
Common symptoms:
- Error log containing: Uncaught Error: Cannot use string offset as an array in /…/class-alg-wc-mppu-data.php:510 WPFactory
- Disabling the plugin resolves the issue. WPFactory
Cause:
- A bug or incorrect data handling in plugin’s code, for instance, when expected data structures (array) are replaced with strings, causing PHP errors.
- Could be triggered by certain product setups, custom checkout flows, or conflict with other plugins.
Solution
- Temporarily disable the plugin, to restore checkout functionality while investigating.
- Check plugin version and update: Ensure you use the latest plugin version; updates often fix such bugs. The plugin changelog shows frequent fixes. WordPress.org+1
- Review your product data: Check if there are products or orders with unusual metadata (variations, custom fields, missing data), these may trigger data-handling issues.
- Test with default theme and only WooCommerce + this plugin active: This helps rule out conflicts with theme or other plugins.
- Enable WP_DEBUG and check PHP error logs: Capture full stack trace of error, helpful to report to plugin developers if needed.
- Contact plugin support (if still broken): Provide error message, WP/WooCommerce/PHP versions, list of active plugins/theme.
Prerequisites
- FTP or hosting access to disable plugin if site becomes inaccessible.
- Backups of site and database.
Additional Notes
- Because this is a critical issue (checkout break), it’s important to test plugin updates first on a staging site.
- Notify users if they hit this issue; offer alternative checkout or temporary disable until fix applied.
