diff --git a/v6.1.12-modrefchange/modrefchange/.info b/v6.1.12-modrefchange/modrefchange/.info
index 7112731..0df0a8f 100644
--- a/v6.1.12-modrefchange/modrefchange/.info
+++ b/v6.1.12-modrefchange/modrefchange/.info
@@ -1 +1 @@
-K8ekbIMbIwtx8vVd3hIGsdHkD2iGIAmyzFp9j/Sj1KU1ZDwo8bInXlWu+2cnsfdGPD4NyEzsYI6EIUeYC29+x572begpse5B0d97ptnJCd2GyZ24YF4ne7GBM8a+Bask+kWf42w8qapfITdeshcDQt3mmpTf2I6F0mFpaFQknz+N8elp++IbhZChjs0XPX0HzbizjVR8MOBcLo/TkgKw4b4f8DjqwmNG+JaIf3Y+/gjTjJnPAzH43P0QO0NLiXG/OEOH2Mn1qThE0lKL5w0wUQ==
\ No newline at end of file
+hp8Rz5f1aqlQcR8AbPVjOjkQI3S9AqASU5CGcWdAc4bOanpJtTuCw1MQWoSn22wRrMkEHEnclQhWfgE6FpMva/d/T2Ovn2HEesI3dZ0x2APOJddCxqcHWZykofDjNy2WmHGZ/+GnCU9NQFIvXAoub4acI0GYU9sHJqPlCnblkk9Sq4QTeOITRsyRwQOLhCc+HtoNtT899Nt9xgoPYD/cPXzA/DU15quSquEqHjotfDod7asH52zlDQPn/n5oyLF9hyGg91AXSoECeSRLrowkpQ==
\ No newline at end of file
diff --git a/v6.1.12-modrefchange/modrefchange/classes/DocumentReferences.php b/v6.1.12-modrefchange/modrefchange/classes/DocumentReferences.php
index c5522e3..5e3944e 100644
--- a/v6.1.12-modrefchange/modrefchange/classes/DocumentReferences.php
+++ b/v6.1.12-modrefchange/modrefchange/classes/DocumentReferences.php
@@ -256,9 +256,31 @@ class DocumentReferences extends ObjectModel
 			WHERE `id_order` = '.(int)$orderId);
 	}
 	
+	public static function getDefaultCounterData()
+	{
+		return array(
+			'counter_start_at' => '',
+			'counter_increment_by' => '',
+			'counter_actual_value' => '',
+			'counter_reset_interval' => '5',
+			'counter_reset_number' => '',
+			'counter_reset_date' => '',
+			'counter_reset_now' => '0',
+			'counter_reference_length_in_use' => '0',
+			'counter_reference_length' => '4',
+			'counter_last_set_date' => date("Y-m-d")
+		);
+	}
+
 	public static function checkForCounterReset($type)
 	{
 		$counterData = json_decode(Configuration::getGlobalValue('counterNumberData'), true);
+		if (!is_array($counterData)) {
+			$counterData = array();
+		}
+		if (!isset($counterData[$type]) || !is_array($counterData[$type])) {
+			$counterData[$type] = self::getDefaultCounterData();
+		}
 		$currentCounterData = $counterData[$type];
 		$today = date("Y-m-d");
 		if ((int)$currentCounterData['counter_reset_interval'] == 0) //reset tyzdna
diff --git a/v6.1.12-modrefchange/modrefchange/modrefchange.php b/v6.1.12-modrefchange/modrefchange/modrefchange.php
index 03cbe2d..3a2fc7a 100644
--- a/v6.1.12-modrefchange/modrefchange/modrefchange.php
+++ b/v6.1.12-modrefchange/modrefchange/modrefchange.php
@@ -192,7 +192,26 @@ class ModRefChange extends Module
 		$helper->table = $this->name;
 		$helper->token = Tools::getAdminTokenLite('AdminModules');
 		$helper->currentIndex = AdminController::$currentIndex.'&configure='.$this->name;
-		return $helper->generateList(json_decode(Configuration::get($this->name), true), $this->fields_list);
+		return $helper->generateList($this->getReferenceNumbersData(), $this->fields_list);
+	}
+
+	private function getReferenceNumbersData()
+	{
+		$referenceNumbersData = json_decode(Configuration::get($this->name), true);
+		if (!is_array($referenceNumbersData)) {
+			$referenceNumbersData = array();
+		}
+		$needsUpdate = false;
+		foreach ($this->initReferenceNumbersData() as $key => $defaultValue) {
+			if (!isset($referenceNumbersData[$key]) || !is_array($referenceNumbersData[$key])) {
+				$referenceNumbersData[$key] = $defaultValue;
+				$needsUpdate = true;
+			}
+		}
+		if ($needsUpdate) {
+			Configuration::updateValue($this->name, json_encode($referenceNumbersData));
+		}
+		return $referenceNumbersData;
 	}
 	
 	public function displayForm()
@@ -486,7 +505,7 @@ class ModRefChange extends Module
 			)
 		);
 		$id_reference_number = (int)Tools::getValue('id_reference_number');
-		$referenceNumbersData = json_decode(Configuration::get($this->name), true);
+		$referenceNumbersData = $this->getReferenceNumbersData();
 		$getAllCounterData = json_decode(Configuration::getGlobalValue('counterNumberData'), true);
 		$helper = new HelperForm();
 		$helper->module = $this;
@@ -691,7 +710,7 @@ class ModRefChange extends Module
 		$customReferenceNumbersArray = array();
 		$counterNumbersArray = array();
 		$id_reference_number = (int)Tools::getValue('id_reference_number');
-		$getAllReferenceNumberData = json_decode(Configuration::get($this->name), true);
+		$getAllReferenceNumberData = $this->getReferenceNumbersData();
 		$getAllCounterData = json_decode(Configuration::getGlobalValue('counterNumberData'), true);
 		$currentCustomOrderReferenceArray = $getAllReferenceNumberData[$id_reference_number - 1];
 		$currentCounterData = $getAllCounterData[$id_reference_number - 1];
@@ -740,7 +759,7 @@ class ModRefChange extends Module
 	private function setReferenceNumberStatus()
 	{
 		$id_reference_number = (int)Tools::getValue('id_reference_number');
-		$getAllReferenceNumberData = json_decode(Configuration::get($this->name), true);
+		$getAllReferenceNumberData = $this->getReferenceNumbersData();
 		if ($getAllReferenceNumberData[$id_reference_number - 1]['activate_reference_number'])
 			$getAllReferenceNumberData[$id_reference_number - 1]['activate_reference_number'] = false;
 		else
diff --git a/v6.1.12-modrefchange/modrefchange/override/classes/order/Order.php b/v6.1.12-modrefchange/modrefchange/override/classes/order/Order.php
index 4e42768..495713f 100644
--- a/v6.1.12-modrefchange/modrefchange/override/classes/order/Order.php
+++ b/v6.1.12-modrefchange/modrefchange/override/classes/order/Order.php
@@ -9,22 +9,30 @@
  
 if (!defined('_PS_VERSION_'))
 	exit;
-}
 
 require_once(_PS_MODULE_DIR_.'modrefchange/classes/DocumentReferences.php');
 
 class Order extends OrderCore
 {
+	private static function loadDocumentReferences()
+	{
+		if (!class_exists('DocumentReferences')) {
+			require_once(_PS_MODULE_DIR_.'modrefchange/classes/DocumentReferences.php');
+		}
+	}
+
 	public function setInvoice($use_existing_payment = false)
 	{
 		if (!$this->hasInvoice()) {
 			parent::setInvoice($use_existing_payment);
+			self::loadDocumentReferences();
 			DocumentReferences::storeReference('invoice', $this->id);
 		}
 	}
-	
+
 	public function setDelivery()
 	{
+		self::loadDocumentReferences();
 		$order_invoice_collection = $this->getInvoicesCollection();
         foreach ($order_invoice_collection as $order_invoice) {
             if ($order_invoice->delivery_number) {
@@ -34,9 +42,10 @@ class Order extends OrderCore
         }
 		parent::setDelivery();
 	}
-	
+
 	public static function generateReference()
 	{
+		self::loadDocumentReferences();
 		return DocumentReferences::storeReference('order');
 	}
 	
@@ -46,7 +55,7 @@ class Order extends OrderCore
             if (Context::getContext()->controller->controller_name == 'Admin') {
                 return false;
             }
-            parent::hasBeenDelivered();
+            return parent::hasBeenDelivered();
         } else {
             if (Tools::getIsset('action'))
                 if (Tools::getValue('action') == 'editProductOnOrder' || Tools::getValue('action') == 'deleteProductLine')
diff --git a/v6.1.12-modrefchange/modrefchange/override/classes/order/OrderInvoice.php b/v6.1.12-modrefchange/modrefchange/override/classes/order/OrderInvoice.php
index 95811a6..f5ec73a 100644
--- a/v6.1.12-modrefchange/modrefchange/override/classes/order/OrderInvoice.php
+++ b/v6.1.12-modrefchange/modrefchange/override/classes/order/OrderInvoice.php
@@ -9,15 +9,23 @@
  
 if (!defined('_PS_VERSION_'))
 	exit;
-}
 
 require_once(_PS_MODULE_DIR_.'modrefchange/classes/DocumentReferences.php');
 
 class OrderInvoice extends OrderInvoiceCore
 {
+	private static function loadDocumentReferences()
+	{
+		if (!class_exists('DocumentReferences')) {
+			require_once(_PS_MODULE_DIR_.'modrefchange/classes/DocumentReferences.php');
+		}
+	}
+
 	public function getInvoiceNumberFormatted($id_lang, $id_shop = null, $oldFormat = false)
 	{
-        $invoiceNumber = DocumentReferences::getReference($this->id, 'invoice')['reference'];
+        self::loadDocumentReferences();
+        $reference = DocumentReferences::getReference($this->id, 'invoice');
+        $invoiceNumber = $reference ? $reference['reference'] : null;
         if ($oldFormat || $invoiceNumber == NULL) {
             return parent::getInvoiceNumberFormatted($id_lang, $id_shop);
         }
diff --git a/v6.1.12-modrefchange/modrefchange/override/classes/pdf/PDF.php b/v6.1.12-modrefchange/modrefchange/override/classes/pdf/PDF.php
index a64c12c..fae54eb 100644
--- a/v6.1.12-modrefchange/modrefchange/override/classes/pdf/PDF.php
+++ b/v6.1.12-modrefchange/modrefchange/override/classes/pdf/PDF.php
@@ -9,14 +9,21 @@
 
 if (!defined('_PS_VERSION_'))
 	exit;
-}
 
 require_once(_PS_MODULE_DIR_.'modrefchange/classes/DocumentReferences.php');
 
 class PDF extends PDFCore
 {
+    private static function loadDocumentReferences()
+    {
+        if (!class_exists('DocumentReferences')) {
+            require_once(_PS_MODULE_DIR_.'modrefchange/classes/DocumentReferences.php');
+        }
+    }
+
     public function render($display = true)
     {
+        self::loadDocumentReferences();
         $render = false;
         $this->pdf_renderer->setFontForLang(Context::getContext()->language->iso_code);
         foreach ($this->objects as $object) {