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