diff --git a/install-dev/upgrade/php/update_customer_default_group.php b/install-dev/upgrade/php/update_customer_default_group.php
index 9ce468a41..253667c3d 100644
--- a/install-dev/upgrade/php/update_customer_default_group.php
+++ b/install-dev/upgrade/php/update_customer_default_group.php
@@ -29,16 +29,19 @@ function update_customer_default_group()
 	$filename = _PS_ROOT_DIR_.'/config/defines.inc.php';
 	$filename_old = str_replace('.inc.', '.old.', $filename);
 	copy($filename, $filename_old);
-	@chmod($filename_old, 0664);	
+	chmod($filename_old, 0664);	
 	$content = file_get_contents($filename);
 	$pattern = "/define\('_PS_DEFAULT_CUSTOMER_GROUP_', (\d)\);/";
 	preg_match($pattern, $content, $matches);
 	if (!defined('_PS_DEFAULT_CUSTOMER_GROUP_'))
-			define('_PS_DEFAULT_CUSTOMER_GROUP_', ((isset($matches[1]) AND is_numeric($matches[1]))? (int)$matches[1] : 3));
-	$ps_customer_group = DB::getInstance()->getValue('SELECT value FROM `'._DB_PREFIX_.'configuration` WHERE name LIKE "PS_CUSTOMER_GROUP"', false);			
-	$str_old = 'define(\'_PS_DEFAULT_CUSTOMER_GROUP_\', '.(int)_PS_DEFAULT_CUSTOMER_GROUP_.');';
-	$str_new = 'define(\'_PS_DEFAULT_CUSTOMER_GROUP_\', '.(int)$ps_customer_group.');';				
-	$content = str_replace($str_old, $str_new, $content);
+			define('_PS_DEFAULT_CUSTOMER_GROUP_', ((isset($matches[1]) AND is_numeric($matches[1]))? $matches[1] : 3));
+	$ps_customer_group = DB::getInstance()->getValue('SELECT value FROM `'._DB_PREFIX_.'configuration` WHERE name LIKE "PS_CUSTOMER_GROUP"', false);
+	if ($ps_customer_group)
+	{		
+		$str_old = 'define(\'_PS_DEFAULT_CUSTOMER_GROUP_\', '.(int)_PS_DEFAULT_CUSTOMER_GROUP_.');';
+		$str_new = 'define(\'_PS_DEFAULT_CUSTOMER_GROUP_\', '.(int)$ps_customer_group.');';
+		$content = str_replace($str_old, $str_new, $content);
+	}
 
 	$carriers = Db::getInstance()->executeS('
 	SELECT `id_carrier`
@@ -50,21 +53,22 @@ function update_customer_default_group()
 	FROM `'._DB_PREFIX_.'configuration`
 	WHERE `name` IN (\'PS_UNIDENTIFIED_GROUP\', \'PS_GUEST_GROUP\')');
 
-	$result = false;
+	$result = true;
 	if (count($carriers) && is_array($carriers) && count($groups) && is_array($groups))
 		foreach ($carriers as $carrier)
 			foreach ($groups as $group)
-				Db::getInstance()->execute('
+				$result &= (bool)Db::getInstance()->execute('
 				INSERT IGNORE INTO `'._DB_PREFIX_.'carrier_group` 
 				VALUES ('.(int)$carrier['id_carrier'].', '.(int)$group['id_group'].')');
 
-	if(file_exists($filename) && is_writable($filename))
-		$result &= (bool)@file_put_contents($filename, $content);
-	if($result === true && file_exists($filename) && file_exists($filename_old))
+	if($result && file_exists($filename) && is_writable($filename))
 	{
-		@unlink($filename_old);
-		@chmod($filename, 0664);
-		return true;
+		$result &= (bool)file_put_contents($filename, $content);
+		if($result && file_exists($filename_old))
+		{
+			$result &= (bool)unlink($filename_old);
+			chmod($filename, 0664);
+		}
 	}
-	return false;
+	return $result;
 }
\ No newline at end of file