> ## Documentation Index
> Fetch the complete documentation index at: https://docs.chainlit.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Migrate to Chainlit v2.0.0

<Note>Join the discord for live updates: [https://discord.gg/AzyvDHWARx](https://discord.gg/AzyvDHWARx)</Note>

## Updating Chainlit

Begin the migration by updating Chainlit to the latest version:

```bash theme={null}
pip install --upgrade chainlit
```

## What changes?

The Chainlit UI (including the copilot) has been completely re-written with Shadcn/Tailwind. This brings several advantages:

1. The codebase is simpler and more contribution friendly.
2. It enabled the new custom element feature.
3. The theme customisation is more powerful.

Full changelog available [here](https://github.com/Chainlit/chainlit/blob/main/CHANGELOG.md#200---2025-01-06).

## How to migrate?

### 1. Regenerate the config file

The following fields have been removed from the `config.toml` file:

1. **follow\_symlink**: Chainlit no longer uses `StaticFiles` to serve files.
2. **font\_family**, **custom\_font**, **\[UI.theme]**: Theme customisation now uses a [separate file](/customisation/theme).
3. **audio**: Chainlit audio streaming has been rework to match the [realtime APIs](/advanced-features/multi-modal).

You can either manually remove those field or remove the `.chainlit/config.toml` file and restart your application.

### 2. Cookie Auth & Cross Origins

All of the authentication mechanisms now use cookie auth instead of directly using a JWT. This change makes Chainlit more secure.

This does not require any change in your app code. However, this implies that Chainlit is now more picky about cross origins (for instance when using a copilot on a website).

If you need to consume a Chainlit app on a different origin, make sure you allow it in the `config.toml` under `allow_origins`.

### 3. Actions

1. The **value** field has replaced with `payload` which accepts a Python dict. This makes actions more useful.
2. The **description** field has been renamed `tooltip`.
3. The field `icon` has been added. You can use any lucide icon name.
4. The **collapsed** field has been removed.

### 4. Copilot Widget Config

1. The **fontFamily** field has been removed. Check the [new custom theme documentation](/customisation/theme).
2. the `button.style` field has been replaced with `button.className`. You can use any tailwind class to style the widget button.