+++
title = "Error handling"
+++

# Error handling

This guide explains how to handle errors in plugins.

## Provide usable defaults

Allow the user to learn your plugin in small steps. Provide a useful default configuration so that:

- The user can get started right away.
- You can avoid unnecessary error messages.

For example, by selecting the first field of an expected type, the panel can display a visualization without any user configuration. If a user explicitly selects a field, then use that one. Otherwise, default to the first field of type `string`:

```ts
const numberField = frame.fields.find(field =>
  options.numberFieldName ? field.name === options.numberFieldName : field.type === FieldType.number
);
```

## Display error messages

To display an error message to the user, `throw` an `Error` with the message you want to display:

```ts
throw new Error('An error occurred');
```

Grafana displays the error message in the top-left corner of the panel.

{{< figure src="/static/img/docs/panel_error.png" class="docs-image--no-shadow" max-width="850px" >}}

Avoid displaying overly-technical error messages to the user. If you want to let technical users report an error, consider logging it instead.

```ts
try {
  failingFunction();
} catch (err) {
  console.error(err);
  throw new Error('Something went wrong');
}
```

> **Note:** Grafana displays the exception message in the UI as written, so we recommend using grammatically correct sentences. For more information, refer to the [Documentation style guide](https://github.com/grafana/grafana/blob/master/contribute/style-guides/documentation-style-guide.md).

Here are some examples of situations where you might want to display an error to the user.

### Invalid query response

Users have full freedom when they create data source queries for panels. If your panel plugin requires a specific format for the query response, then use the panel canvas to guide the user.

```ts
if (!numberField) {
  throw new Error('Query result is missing a number field')
}

if (frame.length === 0) {
  throw new Error('Query returned an empty result')
}
```
