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

# Logs Events

Log events are distributed by Modern.js as events of type `log`.

## Built-in Events

Based on server-side runtime logic, Modern.js provides the following log events:

| Stage          | Message                                       | Level |
| -------------- | --------------------------------------------- | ----- |
| RENDER\_HTML   | App Render To HTML                            | error |
| RENDER\_STREAM | An error occurs during streaming SSR          | error |
| RENDER\_SHELL  | An error occurs during streaming render shell | error |

## Built-in Monitor

In Modern.js, log events are handled by `LoggerMonitor`, which outputs logs to the console.

:::info
The built-in `LoggerMonitor` depends on the [rslog](https://www.npmjs.com/package/rslog) library.
:::

For example, intentionally throwing an error in the project:

```tsx title=routes/page.tsx
import './index.css';

const Index = () => <div className="container-box">{a}</div>;

export default Index;
```

If running normally, you can see the following output in the console:

```shell
> Local:    http://localhost:8080/
> press h + enter to show shortcuts

error   SSR Error - App Prerender, error = ReferenceError: a is not defined
    at Index (/somepath/page.tsx:3:1)
```