Upgrading from 1.6.1 to 1.6.2
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 these files and directories in your "system" folder with the new versions:
Note: If you have any custom developed files in these folders please make copies of them first.
Step 2: Encryption Key
If you are using sessions, open up application/config/config.php and verify you've set an encryption key.
Step 3: Constants File
Copy /application/config/constants.php to your installation, and modify if necessary.
Step 4: Mimes File
Replace /application/config/mimes.php with the dowloaded version. If you've added custom mime types, you'll need to re-add them.
Step 5: Update your user guide
Please also replace your local copy of the user guide with the new version.