diff --git a/app/code/core/Mage/Catalog/Model/Product/Type.php b/app/code/core/Mage/Catalog/Model/Product/Type.php
index e575daaf205..e58889f3d75 100644
--- a/app/code/core/Mage/Catalog/Model/Product/Type.php
+++ b/app/code/core/Mage/Catalog/Model/Product/Type.php
@@ -51,7 +51,7 @@ class Mage_Catalog_Model_Product_Type
     public static function factory($product, $singleton = false)
     {
         $types = self::getTypes();
-        $typeId = $product->getTypeId();
+        $typeId = (string) $product->getTypeId();
 
         if (!empty($types[$typeId]['model'])) {
             $typeModelName = $types[$typeId]['model'];
diff --git a/app/code/core/Mage/Catalog/Model/Resource/Product/Indexer/Price.php b/app/code/core/Mage/Catalog/Model/Resource/Product/Indexer/Price.php
index 9c273473ea5..b7e1a1cc5cd 100644
--- a/app/code/core/Mage/Catalog/Model/Resource/Product/Indexer/Price.php
+++ b/app/code/core/Mage/Catalog/Model/Resource/Product/Indexer/Price.php
@@ -309,6 +309,10 @@ public function reindexProductIds($ids)
      */
     protected function _getIndexer($productTypeId)
     {
+        if ($productTypeId === null) {
+            $productTypeId = '';
+        }
+
         $types = $this->getTypeIndexers();
         if (!isset($types[$productTypeId])) {
             Mage::throwException(Mage::helper('catalog')->__('Unsupported product type "%s".', $productTypeId));
diff --git a/app/code/core/Mage/CatalogInventory/Model/Stock/Status.php b/app/code/core/Mage/CatalogInventory/Model/Stock/Status.php
index 6f1652b53a4..011d66d853d 100644
--- a/app/code/core/Mage/CatalogInventory/Model/Stock/Status.php
+++ b/app/code/core/Mage/CatalogInventory/Model/Stock/Status.php
@@ -183,7 +183,7 @@ public function assignProduct(Mage_Catalog_Model_Product $product, $stockId = 1,
         if (is_null($stockStatus)) {
             $websiteId = $product->getStore()->getWebsiteId();
             $status = $this->getProductStatus($product->getId(), $websiteId, $stockId);
-            $stockStatus = $status[$product->getId()] ?? null;
+            $stockStatus = $status[(string) $product->getId()] ?? null;
         }
 
         $product->setIsSalable($stockStatus);
diff --git a/app/code/core/Mage/Core/Controller/Varien/Router/Standard.php b/app/code/core/Mage/Core/Controller/Varien/Router/Standard.php
index c22e97a0d51..aeb3ebeea31 100644
--- a/app/code/core/Mage/Core/Controller/Varien/Router/Standard.php
+++ b/app/code/core/Mage/Core/Controller/Varien/Router/Standard.php
@@ -406,7 +406,7 @@ public function getModuleByName($moduleName, $modules)
      */
     public function getFrontNameByRoute($routeName)
     {
-        return $this->_routes[$routeName] ?? false;
+        return $this->_routes[(string) $routeName] ?? false;
     }
 
     /**
diff --git a/app/code/core/Mage/Index/Model/Indexer/Abstract.php b/app/code/core/Mage/Index/Model/Indexer/Abstract.php
index 28c22cc78ce..62c1cfbc0ff 100644
--- a/app/code/core/Mage/Index/Model/Indexer/Abstract.php
+++ b/app/code/core/Mage/Index/Model/Indexer/Abstract.php
@@ -110,6 +110,10 @@ public function matchEvent(Mage_Index_Model_Event $event)
      */
     public function matchEntityAndType($entity, $type)
     {
+        if ($entity === null) {
+            $entity = '';
+        }
+
         if (isset($this->_matchedEntities[$entity])) {
             if (in_array($type, $this->_matchedEntities[$entity])) {
                 return true;
diff --git a/lib/Varien/Data/Collection.php b/lib/Varien/Data/Collection.php
index 525a18a44c5..518587dba79 100644
--- a/lib/Varien/Data/Collection.php
+++ b/lib/Varien/Data/Collection.php
@@ -738,6 +738,11 @@ protected function _toOptionHash($valueField = 'id', $labelField = 'name')
     public function getItemById($idValue)
     {
         $this->load();
+
+        if ($idValue === null) {
+            $idValue = '';
+        }
+
         return $this->_items[$idValue] ?? null;
     }
 
diff --git a/lib/Varien/Http/Adapter/Curl.php b/lib/Varien/Http/Adapter/Curl.php
index f3fac843fca..a27bac779c0 100644
--- a/lib/Varien/Http/Adapter/Curl.php
+++ b/lib/Varien/Http/Adapter/Curl.php
@@ -216,7 +216,6 @@ public function read()
      */
     public function close()
     {
-        curl_close($this->_getResource());
         $this->_resource = null;
         return $this;
     }