Nitish Thakrar

You need to change in gtpay-payment.php

replace function by below code.

function process_payment($order_id) {
            global $woocommerce;
            $order = new WC_Order($order_id);
            return array(
	        	'result' => 'success',
				'redirect'	=> $order->get_checkout_payment_url( true )
            );
        }