# Migrate (/migrate)

Choose the guide for the code you're updating. Lumis packages have separate
release numbers, so the guides are grouped by runtime or integration.

| Existing code | Guide |
| --- | --- |
| Elixir 0.6, or parser downloads from before 0.9 | [Elixir upgrades](/migrate/elixir) |
| HTML line divs or helpers that return line terminators | [HTML line markup](/migrate/html-lines) |
| JavaScript-only custom parser and query definitions | [JavaScript custom languages](/migrate/javascript) |
| MDEx with compiled-in grammars | [MDEx parser packages](/migrate/mdex) |
| The Rust `autumnus` crate | [Autumnus to Lumis](/migrate/autumnus) |

For a new project, start with [Installation](/installation). The usage and
formatter pages describe the current API; these guides explain what to change
in an existing application.