# Upgrading from 3.1.8 to 3.1.9

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: Replace config/mimes.php

This config file has received some updates. Please copy it to application/config/mimes.php.