AWS Lambda (sdk) ResourceNotFoundException

Understanding AWS Lambda

AWS Lambda is a serverless compute service provided by Amazon Web Services (AWS) that allows you to run code without provisioning or managing servers. It automatically scales your application by running code in response to each trigger, such as changes in data, shifts in system state, or user actions. Lambda functions can be triggered by various AWS services, making it a versatile tool for building scalable applications.

Identifying the Symptom: ResourceNotFoundException

When working with AWS Lambda, you might encounter the ResourceNotFoundException error. This error typically occurs when the specified resource, such as a Lambda function or an alias, cannot be found. The error message might look something like this:

{ "errorMessage": "ResourceNotFoundException: Function not found: arn:aws:lambda:us-west-2:123456789012:function:my-function", "errorType": "ResourceNotFoundException"}

Exploring the Issue: Why ResourceNotFoundException Occurs

The ResourceNotFoundException is thrown when the AWS Lambda service cannot locate the specified resource. This could be due to several reasons:

• The function name or ARN (Amazon Resource Name) is incorrect.
• The function does not exist in the specified AWS region.
• The resource has been deleted or never created.

For more details on AWS Lambda errors, you can refer to the AWS Lambda API Reference.

Steps to Resolve ResourceNotFoundException

Step 1: Verify the Function Name and ARN

Ensure that the function name or ARN you are using is correct. You can list all your Lambda functions in a specific region using the AWS CLI:

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

Check the output to confirm that the function name and ARN match what you are using in your code or configuration.

Step 2: Check the AWS Region

Lambda functions are region-specific. Make sure you are operating in the correct AWS region. You can specify the region in your AWS CLI commands or SDK configuration. For example:

aws lambda invoke --function-name my-function --region us-west-2 output.txt

Step 3: Confirm Resource Existence

If the function was recently deleted or never created, you will need to create it again. You can create a Lambda function using the AWS Management Console or AWS CLI:

aws lambda create-function --function-name my-function --runtime nodejs14.x --role arn:aws:iam::123456789012:role/execution_role --handler index.handler --zip-file fileb://function.zip --region us-west-2

For detailed instructions, visit the AWS Lambda Getting Started Guide.

Conclusion

By following these steps, you should be able to resolve the ResourceNotFoundException error in AWS Lambda. Always ensure that your resource identifiers are correct and that you are operating in the correct AWS region. For further assistance, consider reaching out to AWS Support.