Understanding AWS Lambda

AWS Lambda is a serverless compute service that allows you to run code without provisioning or managing servers. It automatically scales your application by running code in response to triggers such as changes in data, shifts in system state, or user actions. Lambda functions are the core components where your code resides, and they can be invoked directly or through other AWS services.

Identifying the Symptom: FunctionNotFoundException

When working with AWS Lambda, you might encounter the FunctionNotFoundException. This error typically occurs when you attempt to invoke a Lambda function that does not exist. The error message will indicate that the specified function could not be found, which can halt your application or automation process.

Exploring the Issue: Why FunctionNotFoundException Occurs

The FunctionNotFoundException is triggered when the AWS Lambda service cannot locate the function you are trying to access. This could be due to several reasons, such as a typo in the function name, the function being deleted, or the function existing in a different AWS region than expected.

Common Scenarios Leading to the Error

• Incorrect function name specified in the request.
• The function was deleted or never created.
• Attempting to access the function in the wrong AWS region.

Steps to Resolve FunctionNotFoundException

To resolve the FunctionNotFoundException, follow these steps:

1. Verify the Function Name

Ensure that the function name you are using in your request matches exactly with the name of the Lambda function. Lambda function names are case-sensitive, so double-check for any typos or incorrect casing.

2. Check AWS Region

Lambda functions are region-specific. Make sure you are operating in the correct AWS region where the function is deployed. You can specify the region in your AWS CLI command or SDK configuration. For example, using AWS CLI:

aws lambda list-functions --region us-west-2

This command lists all Lambda functions in the us-west-2 region.

3. Confirm Function Existence

Use the AWS Management Console or AWS CLI to confirm that the function exists. In the console, navigate to the Lambda service and check the list of functions. If using AWS CLI, run:

aws lambda get-function --function-name YourFunctionName --region YourRegion

If the function does not exist, you will need to create it or correct the function name.

Additional Resources

For more information on managing AWS Lambda functions, refer to the official AWS Lambda Developer Guide. If you are new to AWS CLI, consider reviewing the AWS CLI User Guide for detailed instructions on setting up and using the CLI.