Duplicate order – Cannot use a payment_method_nonce more than once.

Hi @tphamdev12

There are only three reasons for a duplicate order that I have ever encountered, none of which were caused by a bug in our plugin.

1. The most common reason is there is some unhandled PHP error thrown by a 3rd party plugin or theme template file that occurs after payment has been take but before the order’s status is updated. The customer thinks the payment wasn’t processed so they attempt the payment again. Typically there will be an entry in the fatal-error log. Id make sure your webserver has the proper permissions to write to that directory so logs are captured.
2. There is a duplicate order but the transaction ID is the same. Some plugins interfere with the WooCommerce order creation logic and the result is a duplicate order gets created. Check to see if your duplicate orders actually have unique transaction ID’s or if it’s the same transaction ID. If it’s the same transaction ID, that means only the order was duplicated and your customer wasn’t actually charged twice.
3. Your webserver’s settings (usually nginx) is resulting in duplicate requests. Nginx can be configured to send a request to a different node if the request is taking too long. This results in duplicate requests being sent to your WordPress site.

Kind Regards,