AWS Lambda: function was created successfully but an error occurred when creating the trigger: Cannot read property 'includes' of undefined

Question

I am trying to create a Lambda function off of the AWS-managed slack-echo-command-python blueprint and whenever I hit create, it comes back with "Your Lambda function "test_lambda_01" was successfully created, but an error occurred when creating the trigger: Cannot read property 'includes' of undefined." I am not sure what this means.

The trigger is supposed to be an AWS API Gateway that is created and attached automatically. I have tried to go create one through the Management Console and then add it to the triggers on the Lambda function manually. It gets added successfully but I get back "502_service_error" when I try to use my Slack slash command. It currently is supposed to accept all call types by default (will change later but I want to get something working).

I have changed the endpoint in the Slack settings to the correct one. I can see it being called in the CloudWatch metrics.

I edited the Lambda Function code to return this on every call, just for testing purposes. I am 99% sure that this is a valid response to give to Slack as most/all of it was copied from an example. It is valid JSON according to https://jsonlint.com/ .

{
    "body": {
        "blocks": [{
                "text": {
                    "text": "*It's 80 degrees right now.*",
                    "type": "mrkdwn"
                },
                "type": "section"
            },
            {
                "text": {
                    "text": "Partly cloudy today and tomorrow",
                    "type": "mrkdwn"
                },
                "type": "section"
            }
        ],
        "response_type": "ephemeral"
    },
    "headers": {
        "Content-Type": "application/json"
    },
    "statusCode": "200"
}

I have tested the Lambda Function with their default test and it returns the above. The API Gateway appears under the triggers. Do I need to attach more permissions to the API Gateway (it already has permission to invoke the lambda function)? Also, what was I doing incorrectly when trying to create the function from the blueprint?

Please let me know if you want any additional information.

Answer 1

You need to stringify the body parameter in the response.

https://docs.aws.amazon.com/apigateway/latest/developerguide/set-up-lambda-proxy-integrations.html

{
    "isBase64Encoded": true|false,
    "statusCode": httpStatusCode,
    "headers": { "headerName": "headerValue", ... },
    "multiValueHeaders": { "headerName": ["headerValue", "headerValue2", ...], ... },
    "body": "..."
}

if you see the body parameter above, it is a string.