End of support notice: On October 7th, 2026, AWS will discontinue support for AWS IoT Greengrass Version 1. After October 7th, 2026, you will no longer be able to access the AWS IoT Greengrass V1 resources. For more information, please visit [Migrate from AWS IoT Greengrass Version 1](https://docs.aws.amazon.com/greengrass/v2/developerguide/migrate-from-v1.html).

# Verify the Lambda function is running on the core device
<a name="lambda-check"></a>

1. From the navigation pane of the [AWS IoT console](https://console.aws.amazon.com/iot/), under **Test**, choose **MQTT test client**.

1. Choose the **Subscribe to topic** tab.

1. Enter **hello/world** into the **Topic filter** and expand the **Additional configuration**.

1. Enter the information listed in each of the following fields:
   + For **Quality of Service**, choose **0**.
   + For **MQTT payload display**, choose **Display payloads as strings**.

    

1. Choose **Subscribe**.

Assuming the Lambda function is running on your device, it publishes messages similar to the following to the `hello/world` topic:

![\[Screenshot of message sent to the hello/world topic with message highlighted.\]](http://docs.aws.amazon.com/greengrass/v1/developerguide/images/gg-get-started-045.png)


Although the Lambda function continues to send MQTT messages to the `hello/world` topic, don't stop the AWS IoT Greengrass daemon. The remaining modules are written with the assumption that it's running.

You can delete the function and subscription from the group:
+ On the groups configuration page, under the **Lambda functions** tab, select the Lambda function you want to remove and choose **Remove**.
+ On the groups configuration page, under the **Subscriptions** tab, choose the subscription, and then choose **Delete**.

The function and subscription are removed from the core during the next group deployment.