> ## Documentation Index
> Fetch the complete documentation index at: https://launchdarkly-preview.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Erlang (server-side) SDK 2.x to 3.0 migration guide

> This topic explains the changes in the server-side Erlang SDK 3.0 release and how to migrate to that version.

> For the complete documentation index, see [llms.txt](/llms.txt). For the full documentation snapshot, see [llms-full.txt](/llms-full.txt).

## Overview

This topic explains the changes in the Erlang (server-side) SDK 3.0 release and how to adapt code that uses a 2.x version of the [Erlang (server-side) SDK](https://hexdocs.pm/launchdarkly_server_sdk/index.html) to use version 3.0 or later.

## Understanding dependency changes

**Version 3.0 requires Gun 2.x**. There are no changes to the Erlang SDK API or functionality. However, version 3.0 now requires [Gun 2.x](https://hex.pm/packages/gun).

If your application depends directly on Gun, or if you have other dependencies that use Gun, then you must ensure that they work with Gun 2.x.