# Debug Lifecycle Configurations in Amazon SageMaker Studio Classic
Debug Lifecycle Configurations

**Important**  
As of November 30, 2023, the previous Amazon SageMaker Studio experience is now named Amazon SageMaker Studio Classic. The following section is specific to using the Studio Classic application. For information about using the updated Studio experience, see [Amazon SageMaker Studio](studio-updated.md).  
Studio Classic is still maintained for existing workloads but is no longer available for onboarding. You can only stop or delete existing Studio Classic applications and cannot create new ones. We recommend that you [migrate your workload to the new Studio experience](studio-updated-migrate.md).

The following topics show how to get information about and debug your lifecycle configurations.

**Topics**
+ [

## Verify lifecycle configuration process from CloudWatch Logs
](#studio-lcc-debug-logs)
+ [

## JupyterServer app failure
](#studio-lcc-debug-jupyterserver)
+ [

## KernelGateway app failure
](#studio-lcc-debug-kernel)
+ [

## Lifecycle configuration timeout
](#studio-lcc-debug-timeout)

## Verify lifecycle configuration process from CloudWatch Logs


Lifecycle configurations only log `STDOUT` and `STDERR`.

`STDOUT` is the default output for bash scripts. You can write to `STDERR` by appending `>&2` to the end of a bash command. For example, `echo 'hello'>&2`. 

Logs for your lifecycle configurations are published to your AWS account using Amazon CloudWatch. These logs can be found in the `/aws/sagemaker/studio` log stream in the CloudWatch console.

1. Open the CloudWatch console at [https://console.aws.amazon.com/cloudwatch/](https://console.aws.amazon.com/cloudwatch/).

1. Choose **Logs** from the left side. From the dropdown menu, select **Log groups**.

1. On the **Log groups** page, search for `aws/sagemaker/studio`. 

1. Select the log group.

1. On the **Log group details** page, choose the **Log streams** tab.

1. To find the logs for a specific app, search the log streams using the following format:

   ```
   domain-id/space-name/app-type/default/LifecycleConfigOnStart
   ```

   For example, to find the lifecycle configuration logs for domain `d-m85lcu8vbqmz`, space name `i-sonic-js`, and application type `JupyterLab`, use the following search string:

   ```
   d-m85lcu8vbqmz/i-sonic-js/JupyterLab/default/LifecycleConfigOnStart
   ```

## JupyterServer app failure
JupyterServer app failure

If your JupyterServer app crashes because of an issue with the attached lifecycle configuration, Studio Classic displays the following error message on the Studio Classic startup screen. 

```
Failed to create SageMaker Studio due to start-up script failure
```

Select the `View script logs` link to view the CloudWatch logs for your JupyterServer app.

In the case where the faulty lifecycle configuration is specified in the `DefaultResourceSpec` of your domain, user profile, or shared space, Studio Classic continues to use the lifecycle configuration even after restarting Studio Classic. 

To resolve this error, follow the steps in [Set Default Lifecycle Configurations for Amazon SageMaker Studio Classic](studio-lcc-defaults.md) to remove the lifecycle configuration script from the `DefaultResourceSpec` or select another script as the default. Then launch a new JupyterServer app.

## KernelGateway app failure
KernelGateway app failure

If your KernelGateway app crashes because of an issue with the attached lifecycle configuration, Studio Classic displays the error message in your Studio Classic Notebook. 

Choose `View script logs` to view the CloudWatch logs for your KernelGateway app.

In this case, your lifecycle configuration is specified in the Studio Classic Launcher when launching a new Studio Classic Notebook. 

To resolve this error, use the Studio Classic launcher to select a different lifecycle configuration or select `No script`.

**Note**  
A default KernelGateway lifecycle configuration specified in `DefaultResourceSpec` applies to all KernelGateway images in the domain, user profile, or shared space unless the user selects a different script from the list presented in the Studio Classic launcher. The default script also runs if `No Script` is selected by the user. For more information on selecting a script, see [Step 3: Launch an application with the lifecycle configuration](studio-lcc-create-console.md#studio-lcc-create-console-step3).

## Lifecycle configuration timeout
Lifecycle configuration timeout

There is a lifecycle configuration timeout limitation of 5 minutes. If a lifecycle configuration script takes longer than 5 minutes to run, Studio Classic throws an error.

To resolve this error, ensure that your lifecycle configuration script completes in less than 5 minutes. 

To help decrease the run time of scripts, try the following:
+ Cut down on necessary steps. For example, limit which conda environments to install large packages in.
+ Run tasks in parallel processes.
+ Use the `nohup` command in your script to ensure that hangup signals are ignored and do not stop the execution of the script.