Upgrading from 2.0.1 to 2.0.2
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" folder and replace your index.php file. If any modifications were made to your index.php they will need to be made fresh in this new one.
Note: If you have any custom developed files in these folders please make copies of them first.
Step 2: Remove loading calls for the Security Library
Security has been moved to the core and is now always loaded automatically. Make sure you remove any loading calls as they will result in PHP errors.
Step 3: Move MY_Security
If you are overriding or extending the Security library, you will need to move it to application/core.
csrf_token_name and csrf_hash have changed to protected class properties. Please use security->get_csrf_hash() and security->get_csrf_token_name() to access those values.