ExpressionEngine® 3 User Guide

Legacy Documentation

You are using the documentation for version 3.5.17. Go here for the latest version or check here for your available upgrades to the latest version.

3.0 Conversion Guidelines


This guide is an overview of the changes you will need to make to have your add-ons up and running under 3.0. The most notable changes to add-ons are the The addon.setup.php File and the new Control Panel Style Reference.

There are some deprecated features and code, so be sure to check the Developer Logs in the control panel for messages regarding method deprecation to make sure your add-on is not calling any deprecated code.

Required Changes

Create an addon.setup.php File

In ExpressionEngine 3.0, all add-ons must have a file called addon.setup.php. It defines basic information about your add-on, such as its name, version, and some namespace. It is a required file, without it your add-on will not be recognized.

To get started, create a file called addon.setup.php in the main directory of your add-on. Then fill it in with this template, changing the values to match your add-on:


return array(
  'author'      => 'Example, Inc',
  'author_url'  => '',
  'name'        => 'Hello World',
  'description' => 'Displays a friendly "Hello world!" message.',
  'version'     => '2.0.0',
  'namespace'   => 'Example\HelloWorld'

Your addon should now be visible in the Add-Ons section of the control panel. See The addon.setup.php File for full documentation of available keys.

Component Changes

Depending on what parts your add-on has, you should also review the following pages:

In-App Documentation

Add-ons can now provide some in-app documentation by including a file in the main directory of the add-on. This file will be parsed as markdown. Please note that the first h1 heading will be ignored. All other headings will automatically be listed in the sidebar.


If you’re just getting started, we recommend reviewing some of the new service documentation as well as the following pages: