############################# Upgrading from 3.1.5 to 3.1.6 #############################

Before performing an update you should take your site offline by replacing the index.php file with a static one.

Step 1: Update your CodeIgniter files

Replace all files and directories in your system/ directory.

.. note:: If you have any custom developed files in these directories, please make copies of them first.

Step 2: Remove usage of the APC Cache driver (deprecation)

The :doc:Cache Library <../libraries/caching> APC driver is now deprecated, as the APC extension is effectively dead, as explained in its PHP Manual page <https://secure.php.net/manual/en/intro.apc.php>_.

If your application happens to be using it, you can switch to another cache driver, as APC support will be removed in a future CodeIgniter version.

.. note:: The driver is still available, but you're strongly encouraged to remove its usage sooner rather than later.