diff --git a/.gitignore b/.gitignore
index 68d38d9ca7817..8ec1104f25535 100644
--- a/.gitignore
+++ b/.gitignore
@@ -48,6 +48,8 @@ atlassian*
 /pub/media/import/*
 !/pub/media/import/.htaccess
 /pub/media/logo/*
+/pub/media/custom_options/*
+!/pub/media/custom_options/.htaccess
 /pub/media/theme/*
 /pub/media/theme_customization/*
 !/pub/media/theme_customization/.htaccess
diff --git a/app/code/Magento/Catalog/etc/adminhtml/system.xml b/app/code/Magento/Catalog/etc/adminhtml/system.xml
index 7a05601fcd666..1d563244f1432 100644
--- a/app/code/Magento/Catalog/etc/adminhtml/system.xml
+++ b/app/code/Magento/Catalog/etc/adminhtml/system.xml
@@ -59,7 +59,7 @@
                 <field id="grid_per_page_values" translate="label comment" type="text" sortOrder="2" showInDefault="1" showInWebsite="1" showInStore="1" canRestore="1">
                     <label>Products per Page on Grid Allowed Values</label>
                     <comment>Comma-separated.</comment>
-                    <validate>validate-per-page-value-list</validate>
+                    <validate>validate-per-page-value-list required-entry</validate>
                 </field>
                 <field id="grid_per_page" translate="label comment" type="text" sortOrder="3" showInDefault="1" showInWebsite="1" showInStore="1" canRestore="1">
                     <label>Products per Page on Grid Default Value</label>
@@ -69,7 +69,7 @@
                 <field id="list_per_page_values" translate="label comment" type="text" sortOrder="4" showInDefault="1" showInWebsite="1" showInStore="1" canRestore="1">
                     <label>Products per Page on List Allowed Values</label>
                     <comment>Comma-separated.</comment>
-                    <validate>validate-per-page-value-list</validate>
+                    <validate>validate-per-page-value-list required-entry</validate>
                 </field>
                 <field id="list_per_page" translate="label comment" type="text" sortOrder="5" showInDefault="1" showInWebsite="1" showInStore="1" canRestore="1">
                     <label>Products per Page on List Default Value</label>
diff --git a/app/code/Magento/Quote/Model/QuoteManagement.php b/app/code/Magento/Quote/Model/QuoteManagement.php
index 8f216b64aa9b0..2fcfd2dfadabb 100644
--- a/app/code/Magento/Quote/Model/QuoteManagement.php
+++ b/app/code/Magento/Quote/Model/QuoteManagement.php
@@ -532,19 +532,7 @@ protected function submitQuote(QuoteEntity $quote, $orderData = [])
             );
             $this->quoteRepository->save($quote);
         } catch (\Exception $e) {
-            if (!empty($this->addressesToSync)) {
-                foreach ($this->addressesToSync as $addressId) {
-                    $this->addressRepository->deleteById($addressId);
-                }
-            }
-            $this->eventManager->dispatch(
-                'sales_model_service_quote_submit_failure',
-                [
-                    'order'     => $order,
-                    'quote'     => $quote,
-                    'exception' => $e
-                ]
-            );
+            $this->rollbackAddresses($quote, $order, $e);
             throw $e;
         }
         return $order;
@@ -611,4 +599,41 @@ protected function _prepareCustomerQuote($quote)
             $shipping->setIsDefaultBilling(true);
         }
     }
+
+    /**
+     * Remove related to order and quote addresses and submit exception to further processing.
+     *
+     * @param Quote $quote
+     * @param \Magento\Sales\Api\Data\OrderInterface $order
+     * @param \Exception $e
+     * @throws \Exception
+     */
+    private function rollbackAddresses(
+        QuoteEntity $quote,
+        \Magento\Sales\Api\Data\OrderInterface $order,
+        \Exception $e
+    ): void {
+        try {
+            if (!empty($this->addressesToSync)) {
+                foreach ($this->addressesToSync as $addressId) {
+                    $this->addressRepository->deleteById($addressId);
+                }
+            }
+            $this->eventManager->dispatch(
+                'sales_model_service_quote_submit_failure',
+                [
+                    'order' => $order,
+                    'quote' => $quote,
+                    'exception' => $e,
+                ]
+            );
+        } catch (\Exception $consecutiveException) {
+            $message = sprintf(
+                "An exception occurred on 'sales_model_service_quote_submit_failure' event: %s",
+                $consecutiveException->getMessage()
+            );
+
+            throw new \Exception($message, 0, $e);
+        }
+    }
 }
diff --git a/app/code/Magento/Shipping/Controller/Adminhtml/Order/Shipment/AddTrack.php b/app/code/Magento/Shipping/Controller/Adminhtml/Order/Shipment/AddTrack.php
index fa83db490e380..c417a202321b2 100644
--- a/app/code/Magento/Shipping/Controller/Adminhtml/Order/Shipment/AddTrack.php
+++ b/app/code/Magento/Shipping/Controller/Adminhtml/Order/Shipment/AddTrack.php
@@ -1,14 +1,27 @@
 <?php
 /**
- *
  * Copyright © Magento, Inc. All rights reserved.
  * See COPYING.txt for license details.
  */
+declare(strict_types=1);
+
 namespace Magento\Shipping\Controller\Adminhtml\Order\Shipment;
 
 use Magento\Backend\App\Action;
+use Magento\Framework\App\Action\HttpPostActionInterface;
+use Magento\Framework\App\ObjectManager;
+use Magento\Framework\Controller\ResultFactory;
+use Magento\Framework\Controller\ResultInterface;
+use Magento\Framework\Exception\LocalizedException;
+use Magento\Framework\Serialize\SerializerInterface;
+use Magento\Sales\Api\Data\ShipmentTrackInterfaceFactory;
+use Magento\Sales\Api\ShipmentRepositoryInterface;
+use Magento\Shipping\Controller\Adminhtml\Order\ShipmentLoader;
 
-class AddTrack extends \Magento\Backend\App\Action
+/**
+ * Add new tracking number to shipment controller.
+ */
+class AddTrack extends Action implements HttpPostActionInterface
 {
     /**
      * Authorization level of a basic admin session
@@ -18,27 +31,54 @@ class AddTrack extends \Magento\Backend\App\Action
     const ADMIN_RESOURCE = 'Magento_Sales::shipment';
 
     /**
-     * @var \Magento\Shipping\Controller\Adminhtml\Order\ShipmentLoader
+     * @var ShipmentLoader
      */
     protected $shipmentLoader;
 
+    /**
+     * @var ShipmentRepositoryInterface
+     */
+    private $shipmentRepository;
+
+    /**
+     * @var ShipmentTrackInterfaceFactory
+     */
+    private $trackFactory;
+
+    /**
+     * @var SerializerInterface
+     */
+    private $serializer;
+
     /**
      * @param Action\Context $context
-     * @param \Magento\Shipping\Controller\Adminhtml\Order\ShipmentLoader $shipmentLoader
+     * @param ShipmentLoader $shipmentLoader
+     * @param ShipmentRepositoryInterface|null $shipmentRepository
+     * @param ShipmentTrackInterfaceFactory|null $trackFactory
+     * @param SerializerInterface|null $serializer
      */
     public function __construct(
         Action\Context $context,
-        \Magento\Shipping\Controller\Adminhtml\Order\ShipmentLoader $shipmentLoader
+        ShipmentLoader $shipmentLoader,
+        ShipmentRepositoryInterface $shipmentRepository = null,
+        ShipmentTrackInterfaceFactory $trackFactory = null,
+        SerializerInterface $serializer = null
     ) {
-        $this->shipmentLoader = $shipmentLoader;
         parent::__construct($context);
+
+        $this->shipmentLoader = $shipmentLoader;
+        $this->shipmentRepository = $shipmentRepository ?: ObjectManager::getInstance()
+            ->get(ShipmentRepositoryInterface::class);
+        $this->trackFactory = $trackFactory ?: ObjectManager::getInstance()
+            ->get(ShipmentTrackInterfaceFactory::class);
+        $this->serializer = $serializer ?: ObjectManager::getInstance()
+            ->get(SerializerInterface::class);
     }
 
     /**
-     * Add new tracking number action
+     * Add new tracking number action.
      *
-     * @return void
-     * @throws \Magento\Framework\Exception\LocalizedException
+     * @return ResultInterface
      */
     public function execute()
     {
@@ -46,28 +86,29 @@ public function execute()
             $carrier = $this->getRequest()->getPost('carrier');
             $number = $this->getRequest()->getPost('number');
             $title = $this->getRequest()->getPost('title');
+
             if (empty($carrier)) {
-                throw new \Magento\Framework\Exception\LocalizedException(__('Please specify a carrier.'));
+                throw new LocalizedException(__('Please specify a carrier.'));
             }
             if (empty($number)) {
-                throw new \Magento\Framework\Exception\LocalizedException(__('Please enter a tracking number.'));
+                throw new LocalizedException(__('Please enter a tracking number.'));
             }
+
             $this->shipmentLoader->setOrderId($this->getRequest()->getParam('order_id'));
             $this->shipmentLoader->setShipmentId($this->getRequest()->getParam('shipment_id'));
             $this->shipmentLoader->setShipment($this->getRequest()->getParam('shipment'));
             $this->shipmentLoader->setTracking($this->getRequest()->getParam('tracking'));
             $shipment = $this->shipmentLoader->load();
             if ($shipment) {
-                $track = $this->_objectManager->create(
-                    \Magento\Sales\Model\Order\Shipment\Track::class
-                )->setNumber(
+                $track = $this->trackFactory->create()->setNumber(
                     $number
                 )->setCarrierCode(
                     $carrier
                 )->setTitle(
                     $title
                 );
-                $shipment->addTrack($track)->save();
+                $shipment->addTrack($track);
+                $this->shipmentRepository->save($shipment);
 
                 $this->_view->loadLayout();
                 $this->_view->getPage()->getConfig()->getTitle()->prepend(__('Shipments'));
@@ -78,16 +119,18 @@ public function execute()
                     'message' => __('We can\'t initialize shipment for adding tracking number.'),
                 ];
             }
-        } catch (\Magento\Framework\Exception\LocalizedException $e) {
+        } catch (LocalizedException $e) {
             $response = ['error' => true, 'message' => $e->getMessage()];
         } catch (\Exception $e) {
             $response = ['error' => true, 'message' => __('Cannot add tracking number.')];
         }
-        if (is_array($response)) {
-            $response = $this->_objectManager->get(\Magento\Framework\Json\Helper\Data::class)->jsonEncode($response);
-            $this->getResponse()->representJson($response);
-        } else {
-            $this->getResponse()->setBody($response);
+
+        if (\is_array($response)) {
+            $response = $this->serializer->serialize($response);
+
+            return $this->resultFactory->create(ResultFactory::TYPE_JSON)->setJsonData($response);
         }
+
+        return $this->resultFactory->create(ResultFactory::TYPE_RAW)->setContents($response);
     }
 }
diff --git a/app/code/Magento/Shipping/Test/Unit/Controller/Adminhtml/Order/Shipment/AddTrackTest.php b/app/code/Magento/Shipping/Test/Unit/Controller/Adminhtml/Order/Shipment/AddTrackTest.php
index cf3bf68e10416..1c9cdb1fa7d5b 100644
--- a/app/code/Magento/Shipping/Test/Unit/Controller/Adminhtml/Order/Shipment/AddTrackTest.php
+++ b/app/code/Magento/Shipping/Test/Unit/Controller/Adminhtml/Order/Shipment/AddTrackTest.php
@@ -6,127 +6,162 @@
 
 namespace Magento\Shipping\Test\Unit\Controller\Adminhtml\Order\Shipment;
 
-use Magento\Backend\App\Action;
+use Magento\Backend\App\Action\Context;
+use Magento\Framework\App\Request\Http;
+use Magento\Framework\App\ResponseInterface;
+use Magento\Framework\App\ViewInterface;
+use Magento\Framework\Controller\ResultFactory;
+use Magento\Framework\Controller\ResultInterface;
 use Magento\Framework\TestFramework\Unit\Helper\ObjectManager as ObjectManagerHelper;
+use Magento\Framework\View\Element\BlockInterface;
+use Magento\Framework\View\LayoutInterface;
+use Magento\Framework\View\Page\Config;
+use Magento\Framework\View\Page\Title;
+use Magento\Framework\View\Result\Page;
+use Magento\Sales\Api\Data\ShipmentTrackInterfaceFactory;
+use Magento\Sales\Model\Order\Shipment;
+use Magento\Sales\Model\Order\Shipment\Track;
+use Magento\Shipping\Controller\Adminhtml\Order\Shipment\AddTrack;
+use Magento\Shipping\Controller\Adminhtml\Order\ShipmentLoader;
 
 /**
- * Class AddTrackTest
+ * Class AddTrackTest covers AddTrack controller.
  *
- * @package Magento\Shipping\Controller\Adminhtml\Order\Shipment
  * @SuppressWarnings(PHPMD.CouplingBetweenObjects)
  */
 class AddTrackTest extends \PHPUnit\Framework\TestCase
 {
     /**
-     * @var \Magento\Shipping\Controller\Adminhtml\Order\ShipmentLoader|\PHPUnit_Framework_MockObject_MockObject
+     * @var ShipmentLoader|\PHPUnit_Framework_MockObject_MockObject
      */
-    protected $shipmentLoader;
+    private $shipmentLoader;
 
     /**
-     * @var \Magento\Shipping\Controller\Adminhtml\Order\Shipment\AddTrack
+     * @var AddTrack
      */
-    protected $controller;
+    private $controller;
 
     /**
-     * @var Action\Context|\PHPUnit_Framework_MockObject_MockObject
+     * @var Context|\PHPUnit_Framework_MockObject_MockObject
      */
-    protected $context;
+    private $context;
 
     /**
-     * @var \Magento\Framework\App\Request\Http|\PHPUnit_Framework_MockObject_MockObject
+     * @var Http|\PHPUnit_Framework_MockObject_MockObject
      */
-    protected $request;
+    private $request;
 
     /**
-     * @var \Magento\Framework\App\ResponseInterface|\PHPUnit_Framework_MockObject_MockObject
+     * @var ResponseInterface|\PHPUnit_Framework_MockObject_MockObject
      */
-    protected $response;
+    private $response;
 
     /**
-     * @var \Magento\Framework\ObjectManager\ObjectManager|\PHPUnit_Framework_MockObject_MockObject
+     * @var  ViewInterface|\PHPUnit_Framework_MockObject_MockObject
      */
-    protected $objectManager;
+    private $view;
 
     /**
-     * @var  \Magento\Framework\App\ViewInterface|\PHPUnit_Framework_MockObject_MockObject
+     * @var Page|\PHPUnit_Framework_MockObject_MockObject
      */
-    protected $view;
+    private $resultPageMock;
 
     /**
-     * @var \Magento\Framework\View\Result\Page|\PHPUnit_Framework_MockObject_MockObject
+     * @var Config|\PHPUnit_Framework_MockObject_MockObject
      */
-    protected $resultPageMock;
+    private $pageConfigMock;
 
     /**
-     * @var \Magento\Framework\View\Page\Config|\PHPUnit_Framework_MockObject_MockObject
+     * @var Title|\PHPUnit_Framework_MockObject_MockObject
      */
-    protected $pageConfigMock;
+    private $pageTitleMock;
 
     /**
-     * @var \Magento\Framework\View\Page\Title|\PHPUnit_Framework_MockObject_MockObject
+     * @var ShipmentTrackInterfaceFactory|\PHPUnit_Framework_MockObject_MockObject
      */
-    protected $pageTitleMock;
+    private $trackFactory;
 
+    /**
+     * @var ResultInterface|\PHPUnit_Framework_MockObject_MockObject
+     */
+    private $rawResult;
+
+    /**
+     * @inheritdoc
+     */
     protected function setUp()
     {
         $objectManagerHelper = new ObjectManagerHelper($this);
         $this->shipmentLoader = $this->getMockBuilder(
-            \Magento\Shipping\Controller\Adminhtml\Order\ShipmentLoader::class
+            ShipmentLoader::class
         )
             ->disableOriginalConstructor()
             ->setMethods(['setShipmentId', 'setOrderId', 'setShipment', 'setTracking', 'load'])
             ->getMock();
         $this->context = $this->createPartialMock(
-            \Magento\Backend\App\Action\Context::class,
+            Context::class,
             [
                 'getRequest',
                 'getResponse',
                 'getRedirect',
                 'getObjectManager',
                 'getTitle',
-                'getView'
+                'getView',
+                'getResultFactory'
             ]
         );
         $this->response = $this->createPartialMock(
-            \Magento\Framework\App\ResponseInterface::class,
+            ResponseInterface::class,
             ['setRedirect', 'sendResponse', 'setBody']
         );
-        $this->request = $this->getMockBuilder(\Magento\Framework\App\Request\Http::class)
+        $this->request = $this->getMockBuilder(Http::class)
             ->disableOriginalConstructor()->getMock();
-        $this->objectManager = $this->createPartialMock(
-            \Magento\Framework\ObjectManager\ObjectManager::class,
-            ['create', 'get']
-        );
-        $this->view = $this->createMock(\Magento\Framework\App\ViewInterface::class);
-        $this->resultPageMock = $this->getMockBuilder(\Magento\Framework\View\Result\Page::class)
+        $this->view = $this->createMock(ViewInterface::class);
+        $this->resultPageMock = $this->getMockBuilder(Page::class)
             ->disableOriginalConstructor()
             ->getMock();
-        $this->pageConfigMock = $this->getMockBuilder(\Magento\Framework\View\Page\Config::class)
+        $this->pageConfigMock = $this->getMockBuilder(Config::class)
             ->disableOriginalConstructor()
             ->getMock();
-        $this->pageTitleMock = $this->getMockBuilder(\Magento\Framework\View\Page\Title::class)
+        $this->pageTitleMock = $this->getMockBuilder(Title::class)
             ->disableOriginalConstructor()
             ->getMock();
+        $this->trackFactory = $this->getMockBuilder(ShipmentTrackInterfaceFactory::class)
+            ->disableOriginalConstructor()
+            ->setMethods(['create'])
+            ->getMockForAbstractClass();
+        $this->rawResult = $this->getMockBuilder(ResultInterface::class)
+            ->disableOriginalConstructor()
+            ->setMethods(['setContents'])
+            ->getMockForAbstractClass();
+        $resultFactory = $this->getMockBuilder(ResultFactory::class)
+            ->disableOriginalConstructor()
+            ->setMethods(['create'])
+            ->getMockForAbstractClass();
         $this->context->expects($this->once())
             ->method('getRequest')
             ->will($this->returnValue($this->request));
         $this->context->expects($this->once())
             ->method('getResponse')
             ->will($this->returnValue($this->response));
-        $this->context->expects($this->once())
-            ->method('getObjectManager')
-            ->will($this->returnValue($this->objectManager));
         $this->context->expects($this->once())
             ->method('getView')
             ->will($this->returnValue($this->view));
+        $resultFactory->expects($this->once())
+            ->method('create')
+            ->willReturn($this->rawResult);
+        $this->context->expects($this->once())
+            ->method('getResultFactory')
+            ->willReturn($resultFactory);
         $this->controller = $objectManagerHelper->getObject(
-            \Magento\Shipping\Controller\Adminhtml\Order\Shipment\AddTrack::class,
+            AddTrack::class,
             [
                 'context' => $this->context,
                 'shipmentLoader' => $this->shipmentLoader,
                 'request' => $this->request,
                 'response' => $this->response,
-                'view' => $this->view
+                'view' => $this->view,
+                'trackFactory' => $this->trackFactory,
             ]
         );
     }
@@ -144,7 +179,7 @@ public function testExecute()
         $tracking = [];
         $shipmentData = ['items' => [], 'send_email' => ''];
         $shipment = $this->createPartialMock(
-            \Magento\Sales\Model\Order\Shipment::class,
+            Shipment::class,
             ['addTrack', '__wakeup', 'save']
         );
         $this->request->expects($this->any())
@@ -152,8 +187,10 @@ public function testExecute()
             ->will(
                 $this->returnValueMap(
                     [
-                        ['order_id', null, $orderId], ['shipment_id', null, $shipmentId],
-                        ['shipment', null, $shipmentData], ['tracking', null, $tracking],
+                        ['order_id', null, $orderId],
+                        ['shipment_id', null, $shipmentId],
+                        ['shipment', null, $shipmentData],
+                        ['tracking', null, $tracking],
                     ]
                 )
             );
@@ -183,14 +220,13 @@ public function testExecute()
         $this->shipmentLoader->expects($this->once())
             ->method('load')
             ->will($this->returnValue($shipment));
-        $track = $this->getMockBuilder(\Magento\Sales\Model\Order\Shipment\Track::class)
+        $track = $this->getMockBuilder(Track::class)
             ->disableOriginalConstructor()
             ->setMethods(['__wakeup', 'setNumber', 'setCarrierCode', 'setTitle'])
             ->getMock();
-        $this->objectManager->expects($this->atLeastOnce())
+        $this->trackFactory->expects($this->once())
             ->method('create')
-            ->with(\Magento\Sales\Model\Order\Shipment\Track::class)
-            ->will($this->returnValue($track));
+            ->willReturn($track);
         $track->expects($this->once())
             ->method('setNumber')
             ->with($number)
@@ -206,8 +242,8 @@ public function testExecute()
         $this->view->expects($this->once())
             ->method('loadLayout')
             ->will($this->returnSelf());
-        $layout = $this->createMock(\Magento\Framework\View\LayoutInterface::class);
-        $menuBlock = $this->createPartialMock(\Magento\Framework\View\Element\BlockInterface::class, ['toHtml']);
+        $layout = $this->createMock(LayoutInterface::class);
+        $menuBlock = $this->createPartialMock(BlockInterface::class, ['toHtml']);
         $html = 'html string';
         $this->view->expects($this->once())
             ->method('getLayout')
@@ -235,9 +271,10 @@ public function testExecute()
         $this->pageConfigMock->expects($this->any())
             ->method('getTitle')
             ->willReturn($this->pageTitleMock);
-        $this->response->expects($this->once())
-            ->method('setBody')
-            ->with($html);
-        $this->assertNull($this->controller->execute());
+        $this->rawResult->expects($this->once())
+            ->method('setContents')
+            ->with($html)
+            ->willReturnSelf();
+        $this->assertInstanceOf(ResultInterface::class, $this->controller->execute());
     }
 }
diff --git a/app/code/Magento/Ui/view/base/web/js/lib/core/storage/local.js b/app/code/Magento/Ui/view/base/web/js/lib/core/storage/local.js
index 87b5b2f5fe8fe..038907c21224d 100644
--- a/app/code/Magento/Ui/view/base/web/js/lib/core/storage/local.js
+++ b/app/code/Magento/Ui/view/base/web/js/lib/core/storage/local.js
@@ -79,7 +79,7 @@ define([
 
     /**
      * Extracts and parses data stored in localStorage by the
-     * key specified in 'root' varaible.
+     * key specified in 'root' variable.
      *
      * @returns {Object}
      */
diff --git a/app/code/Magento/Ui/view/base/web/js/lib/validation/rules.js b/app/code/Magento/Ui/view/base/web/js/lib/validation/rules.js
index d765f842a0895..97b47f77beeab 100644
--- a/app/code/Magento/Ui/view/base/web/js/lib/validation/rules.js
+++ b/app/code/Magento/Ui/view/base/web/js/lib/validation/rules.js
@@ -920,12 +920,12 @@ define([
         ],
         'validate-per-page-value-list': [
             function (value) {
-                var isValid = utils.isEmpty(value),
+                var isValid = true,
                     values = value.split(','),
                     i;
 
-                if (isValid) {
-                    return true;
+                if (utils.isEmpty(value)) {
+                    return isValid;
                 }
 
                 for (i = 0; i < values.length; i++) {
diff --git a/lib/web/mage/gallery/gallery.js b/lib/web/mage/gallery/gallery.js
index 15c3d01cf2be3..2ed3f8b0d620c 100644
--- a/lib/web/mage/gallery/gallery.js
+++ b/lib/web/mage/gallery/gallery.js
@@ -141,7 +141,7 @@ define([
             this.setupBreakpoints();
             this.initFullscreenSettings();
 
-            this.settings.$element.on('mouseup', '.fotorama__stage__frame', function () {
+            this.settings.$element.on('mousedown', '.fotorama__stage__frame', function () {
                 if (
                     !$(this).parents('.fotorama__shadows--left, .fotorama__shadows--right').length &&
                     !$(this).hasClass('fotorama-video-container')
diff --git a/lib/web/mage/validation.js b/lib/web/mage/validation.js
index dfa35473176b9..a57191fd4aff4 100644
--- a/lib/web/mage/validation.js
+++ b/lib/web/mage/validation.js
@@ -1431,10 +1431,14 @@
         ],
         'validate-per-page-value-list': [
             function (v) {
-                var isValid = !$.mage.isEmpty(v),
+                var isValid = true,
                     values = v.split(','),
                     i;
 
+                if ($.mage.isEmpty(v)) {
+                    return isValid;
+                }
+
                 for (i = 0; i < values.length; i++) {
                     if (!/^[0-9]+$/.test(values[i])) {
                         isValid = false;