# ErrorObserver

The **ErrorObserver** module defines the listener to observe errors.

## onUnhandledException

onUnhandledException(errMsg: string): void;

Called when an unhandled exception occurs in the JS runtime.

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| errMsg | string | No| Message and error stack trace about the exception.|

**Example**    

```ts
import errorManager from '@ohos.application.errorManager';

let observer = {
    onUnhandledException(errorMsg) {
        console.log('onUnhandledException, errorMsg: ' + JSON.stringify(errorMsg));
    }
}
errorManager.registerErrorObserver(observer)
```