A smoothly functioning checkout system is the backbone of any multi-vendor platform. If a customer completes a purchase, but the backend architecture crashes while assigning the order rows, your checkout pipeline breaks. Customers see a generic failure message, and your vendor commissions do not calculate.
When you check your server logs, you will find an explicit TypeError referencing the OrderManager class. Standard marketplace documentation often suggests “deactivating third-party checkout extensions.” This is ineffective. This error points to a strict type-hinting mismatch inside your database or hook structures, where an order processing query is passing an unexpected data type during the commission routing sequence.
Below is the technical breakdown of why this routing blockage happens and the exact methods to restore your vendor order mappings safely.
The Error Snippet
When a customer attempts to pay for a combined vendor cart or an administrator views order states, your server’s error_log will capture this trace:
Plaintext
PHP Fatal error: Uncaught TypeError: WeDevs\Dokan\Order\OrderManager::is_order_for_vendor(): Argument #1 ($order) must be of type WP_Order, int given in /wp-content/plugins/dokan-lite/includes/Order/OrderManager.php:280
Stack trace:
#0 /wp-content/plugins/dokan-lite/includes/Order/OrderHooks.php(114): WeDevs\Dokan\Order\OrderManager->is_order_for_vendor()
#1 /wp-includes/class-wp-hook.php(324): WeDevs\Dokan\Order\OrderHooks->split_vendor_orders()
Why This Happens (The Real Technical Cause)
The function is_order_for_vendor() checks whether a specific purchase belongs to a vendor’s store before calculating splits. To do this safely, modern versions of the marketplace core use strict PHP type-hinting, requiring the input variable to be a fully instantiated WC_Order object.
This fatal error occurs due to an Argument Type Mismatch during the order split execution phase.
Certain legacy payment gateways, third-party PDF invoice extensions, or custom checkout customization tools hook into the default checkout actions (like woocommerce_checkout_order_processed) and pass a raw integer Order ID instead of a structured order data object.
When the multi-vendor core intercepts this action to split the items into sub-orders, it expects a rich object payload. Because it receives a raw integer array or a flat number instead, the strict type guard inside OrderManager.php rejects the parameter and triggers an immediate fatal exception to prevent corrupt revenue logs from hitting your database.
How to Fix It Safely (Step-by-Step Solutions)
Follow these direct procedural steps to implement a defensive type wrapper or sanitize custom checkout processing sequences.
Fix 1: Implement an Explicit Object Casting Safe Guard
If the error is pointing to a structural filter or template hook within your child theme’s functions.php file or a custom marketplace customization snippet, you must manually check and type-cast the variable before it hits the validation engine.
Locate your custom hooks or the execution snippet handling order assignments and adapt the parameter check using this defensive strategy:
PHP
add_action( 'woocommerce_checkout_order_processed', function( $order_mixed ) {
// 1. Check if the incoming argument is a raw integer Order ID
if ( is_numeric( $order_mixed ) ) {
// Force instantiate the proper WooCommerce Order Object instance
$order_object = wc_get_order( $order_mixed );
} else {
$order_object = $order_mixed;
}
// 2. Only proceed if we successfully built a valid object framework
if ( is_a( $order_object, 'WC_Order' ) ) {
// Run your custom vendor splitting or tracking logic here safely
}
}, 9 ); // Priority 9 ensures this executes right before standard marketplace filters kick in
Fix 2: Overwrite Class Routing Instability via a Global Core Filter
If the error stems directly from an unpatched conflict between your core multi-vendor code and an external premium payment gateway extension, you can place a temporary type-sanitization filter directly inside your utility plugins file to intercept and convert data streams cleanly.
1.Access your child theme configuration paths:
Step 1.
Log into your server file architecture using FTP or an online File Manager. Open /wp-content/themes/[your-active-theme]/ and edit your functions.php file.
2.Inject a parameter wrapper to intercept early triggers:
Step 2.
Paste the following code logic block at the root of the file. This filters the data stream during background checkouts, validating that integers are converted to objects before the strict core manager files handle commission allocations:
PHP
add_filter( 'dokan_ensure_vendor_order_object', function( $potential_id ) {
if ( ! is_object( $potential_id ) && function_exists( 'wc_get_order' ) ) {
return wc_get_order( $potential_id );
}
return $potential_id;
});
3.Flush your server’s memory allocation structures:
Step 3.
Navigate to your WordPress administrative dashboard control center, access your performance optimization tools (such as LiteSpeed Cache, Redis settings, or OPcache tools), and select Purge All / Flush Cache. This forces your PHP compiler to instantly process the updated routing constraints, restoring your order processing workflows smoothly.