Here are some tools to help you identify issues if results aren't showing as you expect.

## Logger

The [logger](🔗) logs information about your experiments to help you with debugging.

You can customize the [log level](🔗) to the kind of information you want to track and specify where log information is sent. We've also developed [default logger implementations](🔗) for some SDKs.

## Error handler

The [error handler](🔗) is called when unknown experiment keys or event keys are referenced. You can provide your own custom error handler logic to standardize across your production environment.

## Notification listeners

Use notification listeners to trigger callbacks when certain actions are triggered in the SDK.

Currently, we support two types of listeners:

• `ACTIVATE` triggers a callback with the experiment, user ID, attributes, variation, and the impression event.

• `TRACK` triggers a callback with the event key, user ID, attributes, and event tags.

## Additional resources

The additional information can be found in the:

• Optimizely's [Support Knowledge Base](🔗), which has help and support topics in addition to strategy and feature documentation.

• The [developer community](🔗), where you can join other developers and learn more about Optimizely’s SDKs.

If you need more help with troubleshooting, please [contact support](🔗).