Is your Drupal site up to date?

First and foremost, it is very important that you are running the latest version of Drupal Core and have the most recent updates to all of your contributed modules. To easily update your Drupal site, it is highly recommended that you use Drush. Otherwise, please refer to https://drupal.org/upgrade for more information.

The DrupalGap module and Application Development Kit can be used to build mobile apps and web apps for Drupal websites.