--- file.inc	2017-03-01 12:10:59.812604531 +0100
+++ file.inc.php	2017-03-01 12:11:01.820687919 +0100
@@ -607,6 +607,11 @@
     $file->original = entity_load_unchanged('file', $file->fid);
   }
 
+  // Add default location if location empty
+  if(!isset($file->upload_location || empty($file->upload_location)) {
+    $file->upload_location = 'private://';
+  }
+
   module_invoke_all('file_presave', $file);
   module_invoke_all('entity_presave', $file, 'file');