When syncing a large product catalog with an external inventory management system or a mobile app via the WooCommerce REST API, you rely on pagination parameters (like ?page=2&per_page=100) to pull data in manageable batches. A disruptive API bug can break this sync flow: the API request succeeds, but it returns the exact same batch of products on page 2 that it did on page 1, or it cuts off the sync prematurely and hides the rest of your catalog.

This data synchronization failure is caused by an API parameter collision within your server's routing rewrite rules. When a third-party plugin or an asset optimization utility registers custom query variables, it can accidentally overwrite the core WordPress global pagination parameter (paged). When your external ERP system requests page 2 of your product data, your server gets confused by the parameter conflict, ignores the pagination instruction, and repeatedly serves the first page of results instead.

The Solution

Resolving API pagination drops requires isolating plugin rewrite rules and explicitly forcing your server to respect core API pagination arguments.

  1. Reset Your Store Permalink Cache: Navigate to Settings > Permalinks in your WordPress dashboard panel. Scroll straight to the bottom of the screen and click the Save Changes button without making any modifications. This flushes and rebuilds your site's virtual routing rules.

  2. Deactivate Conflicting Pagination Interceptors: Add this code snippet to your child theme's functions.php file to intercept incoming REST API requests and force the system to prioritize core WooCommerce pagination variables over conflicting theme filters:

PHP
 
add_filter('rest_product_query', 'fix_api_pagination_parameter_collision', 99, 2);
function fix_api_pagination_parameter_collision($args, $request) {
    $current_page = $request->get_param('page');
    if (!empty($current_page)) {
        $args['paged'] = absint($current_page); // Guarantees the database engine moves to the correct page batch
    }
    return $args;
}

  1. Audit the API Response Headers: Use an API testing tool (like Postman) to run a sample request against your catalog. Check the return headers for X-WP-Total and X-WP-TotalPages to verify that your server is accurately calculating and reporting the full size of your product catalog.