# CodeIgniter User Guide Version 1.7.3

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# Upgrading from 1.6.3 to 1.7.0

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 these files and directories in your "system" folder with the new versions:

- system/codeigniter
- system/database
- system/helpers
- system/language
- system/libraries

Note: If you have any custom developed files in these folders please make copies of them first.

## Step 2: Update your Session Table

If you are using the Session class in your application, AND if you are storing session data to a database, you must add a new column named user_data to your session table. Here is an example of what this column might look like for MySQL: `user_data text NOT NULL`

To add this column you will run a query similar to this:

`ALTER TABLE `ci_sessions` ADD `user_data` text NOT NULL`

You'll find more information regarding the new Session functionality in the Session class page.

## Step 3: Update your Validation Syntax

This is an optional, but recommended step, for people currently using the Validation class. CI 1.7 introduces a new Form Validation class, which deprecates the old Validation library. We have left the old one in place so that existing applications that use it will not break, but you are encouraged to migrate to the new version as soon as possible. Please read the user guide carefully as the new library works a little differently, and has several new features.

## Step 4: Update your user guide

Please replace your local copy of the user guide with the new version, including the image files.