############################# Upgrading from 3.0.6 to 3.1.0 #############################

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: Check your PHP version

We recommend always running versions that are currently supported <https://secure.php.net/supported-versions.php>_, which right now is at least PHP 5.6.

PHP 5.2.x versions are now officially not supported by CodeIgniter, and while 5.3.7+ may be at least runnable, we strongly discourage you from using any PHP versions below the ones listed on the PHP.net Supported Versions <https://secure.php.net/supported-versions.php>_ page.

Step 3: If you're using the 'odbc' database driver, check for usage of Query Builder

:doc:Query Builder <../database/query_builder> functionality and escape() can no longer be used with the 'odbc' database driver.

This is because, due to its nature, the ODBC extension for PHP <https://secure.php.net/odbc>_ does not provide a function that allows to safely escape user-supplied strings for usage inside an SQL query (which our :doc:Query Builder <../database/query_builder> relies on).

Thus, user inputs MUST be bound, as shown in :doc:Running Queries <../database/queries>, under the "Query Bindings" section.