There was an error processing your order. Please contact us or try again later.

[Loginname]

magento 1.9.3.7

<?php
//https://magento.stackexchange.com/questions/223220/creating-order-programatically-showing-wrong-grand-total

	error_reporting(E_ALL);
	require 'app/Mage.php';
	Mage::init();
	Mage::app('default');
	$storeId = Mage::app()->getStore()->getId();
  $Quote = Mage::getModel('sales/quote')->setStoreId($storeId);
  $Customer = Mage::getModel('customer/customer')->load(410); // insert customer ID  
	$_product = Mage::getModel('catalog/product')->load(168789);
	
	
   // Assign Customer To Sales Order Quote
    $Quote->assignCustomer($Customer);
    $address =  $Customer->getDefaultBillingAddress();
    $Quote->getBillingAddress()->importCustomerAddress($address);
    $Quote->getShippingAddress()->importCustomerAddress($address);
    $Quote->setSendCconfirmation(0);

    // Loop to add order. $Item contains the Sku, Qty, Price
    try 
    {
      $Quote->addProduct($_product, new Varien_Object(array('qty' => 1)));
      $Quote->save();
      $QuoteItem = $Quote->getItemByProduct($_product);
      $QuoteItem->setOriginalCustomPrice(49);
      $QuoteItem->setCustomPrice(49);
      $QuoteItem->setIsSuperMode(true);
      $QuoteItem->save();
    }
    catch (Exception $e) 
    {
      echo 'Caught exception: ',  $e->getMessage(), "<br>";
      print "Product ID: " . $_product->getId() . "<br>\n";
      print "Product Sku: " . $_product->getSku() . " - " . $_product->getName() . "<hr>\n";
    }

		//saving order
    try 
    {
        $Quote->collectTotals()->save();
        $Quote->getShippingAddress()
            ->setCollectShippingRates(true)
            ->collectShippingRates()
            ->setShippingMethod('flatrate_flatrate');
        $Quote->getPayment()->setMethod('paypal_express');
        // Create Order From Quote
         $service = Mage::getModel('sales/service_quote', $Quote);
         $service->submitAll();
         $increment_id = $service->getOrder()->getRealOrderId();
    }
    catch (Exception $e) { echo $e->getTraceAsString(); }
  	catch (Mage_Core_Exception $e) { echo $e->getMessage();	} 
 
?>

any idea what I do wrong?

[Loginname]

exception.log shows this:
Exception: PayPal response hasn't required fields.

now, what field am I missing?

[Loginname]

my goal is:

I'm having 15000 orders created in cubecart, that I want imported. Most orders are complete, but nice to have for historic data. About 100 orders are pending....

As a worse case we can maybe use the old system to process old orders.