# 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, 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 page.

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

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 does not provide a function that allows to safely escape user-supplied strings for usage inside an SQL query (which our Query Builder relies on).

Thus, user inputs MUST be bound, as shown in Running Queries, under the “Query Bindings” section.