# CodeIgniter User Guide Version 2.2.0

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# Upgrading from 2.0.0 to 2.0.1

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: Replace config/mimes.php

This config file has been updated to contain more mime types, please copy it to `application/config/mimes.php`.

## Step 3: Check for forms posting to default controller

The default behavior for `form_open()` when called with no parameters used to be to post to the default controller, but it will now just leave an empty action="" meaning the form will submit to the current URL. If submitting to the default controller was the expected behavior it will need to be changed from:

`echo form_open(); //<form action="" method="post" accept-charset="utf-8">`

to use either a / or `base_url()`:

`echo form_open('/'); //<form action="http://example.com/index.php/" method="post" accept-charset="utf-8">
echo form_open(base_url()); //<form action="http://example.com/" method="post" accept-charset="utf-8">`