diff --git a/install-dev/upgrade/php/generate_ntree.php b/install-dev/upgrade/php/generate_ntree.php
index 102d10e2c..a9c12ca4a 100644
--- a/install-dev/upgrade/php/generate_ntree.php
+++ b/install-dev/upgrade/php/generate_ntree.php
@@ -28,8 +28,9 @@ function generate_ntree()
 {
 	$categories = Db::getInstance()->executeS('SELECT id_category, id_parent FROM '._DB_PREFIX_.'category ORDER BY id_parent ASC, position ASC');
 	$categoriesArray = array();
-	foreach ($categories AS $category)
-		$categoriesArray[(int)$category['id_parent']]['subcategories'][(int)$category['id_category']] = 1;
+	if (is_array($categories))
+		foreach ($categories AS $category)
+			$categoriesArray[(int)$category['id_parent']]['subcategories'][(int)$category['id_category']] = 1;
 	$n = 1;
 	generate_ntree_subTree($categoriesArray, 1, $n);
 }
diff --git a/install-dev/upgrade/php/migrate_orders.php b/install-dev/upgrade/php/migrate_orders.php
index 96160fa4b..3a716b47a 100644
--- a/install-dev/upgrade/php/migrate_orders.php
+++ b/install-dev/upgrade/php/migrate_orders.php
@@ -122,7 +122,9 @@ function migrate_orders()
 		if ($sum_total_products > 0)
 			$average_tax_used +=  $sum_tax_amount / $sum_total_products;
 		$average_tax_used = round($average_tax_used, 4);
-		$carrier_tax_rate = 1 + ((float)$order['carrier_tax_rate'] / 100);
+		$carrier_tax_rate = 1;
+		if (isset($order['carrier_tax_rate']))
+			$carrier_tax_rate + ((float)$order['carrier_tax_rate'] / 100);
 
 		$total_discount_tax_excl = $order['total_discounts'] / $average_tax_used;
 		$order['total_discounts_tax_incl'] = (float)$order['total_discounts'];
diff --git a/install-dev/upgrade/php/update_order_canada.php b/install-dev/upgrade/php/update_order_canada.php
index 79413b8fe..1c23fa8b6 100644
--- a/install-dev/upgrade/php/update_order_canada.php
+++ b/install-dev/upgrade/php/update_order_canada.php
@@ -57,6 +57,7 @@ function update_order_canada()
 		$default_price_display_method = Db::getInstance()->getValue('SELECT price_display_method
 			FROM `'._DB_PREFIX_.'group` WHERE id_group=1');
 		$values = '';
+		if (is_array($id_order_list))
 		foreach ($id_order_list as $order)
 		{
 			$amount = array();