In case you have not added the Cognito libraries to your application, be sure to add them:

```yaml
 environment:
   sdk: ">=2.15.0 <3.0.0"

 dependencies:
   flutter:
     sdk: flutter

   amplify_flutter: ^0.6.0
   amplify_api: ^0.6.0
   # Be sure that this is added
   amplify_auth_cognito: ^0.6.0
```

Afterwards add the following code to your app before you configure Amplify:

```dart
await Amplify.addPlugins([AmplifyAuthCognito(), AmplifyAPI(modelProvider: ModelProvider.instance)]);
```