> For AI agents: the complete documentation index is available at /llms.txt, the full documentation bundle is available at /llms-full.txt.

# server.htmlFallback

- **Type:** `false | 'index'`
- **Default:** `'index'`

Whether to enable HTML fallback.

## Default behavior

By default, when the request meets the following conditions and the corresponding resource is not found, it will fallback to `index.html`:

- The request is a `GET` or `HEAD` request
- Which accepts `text/html` (the request header accept type is `text/html` or `*/*`)

```ts title="rsbuild.config.ts"
export default {
  server: {
    htmlFallback: 'index',
  },
};
```

## Disable

If you do not want to enable HTML fallback, you can set `server.htmlFallback` to `false`.

```ts title="rsbuild.config.ts"
export default {
  server: {
    htmlFallback: false,
  },
};
```

## Customize

If `server.htmlFallback` cannot meet your needs, you can use [server.historyApiFallback](/config/server/history-api-fallback.md) for more flexible settings.