AWS API Gateway: Execution failed due to configuration error: Invalid JSON in response

Question

I have an API gateway setup with a Custom Authorizer that calls a Lambda function. For testing purposes I copied the example from here: http://docs.aws.amazon.com/apigateway/latest/developerguide/api-gateway-create-api-as-simple-proxy-for-lambda.html#api-gateway-proxy-integration-lambda-function-nodejs

I get the same answer as in the documentation but when I test the authorizer I get this stacktrace:

    Endpoint request body after transformations: {"type":"TOKEN","authorizationToken":"test","methodArn":"arn:aws:execute-api:ap-southeast-2:893445519708:uyue0zqh15/null/GET/"}
    Authorizer result body before parsing: {"statusCode":200,"headers":{"x-custom-header":"my custom header value"},"body":"{\"message\":\"Hello World!\",\"input\":{\"type\":\"TOKEN\",\"authorizationToken\":\"test\",\"methodArn\":\"arn:aws:execute-api:ap-southeast-2:893445519708:uyue0zqh15/null/GET/\"}}"}
    Execution failed due to configuration error: Invalid JSON in response: {"statusCode":200,"headers":{"x-custom-header":"my custom header value"},"body":"{\"message\":\"Hello World!\",\"input\":{\"type\":\"TOKEN\",\"authorizationToken\":\"test\",\"methodArn\":\"arn:aws:execute-api:ap-southeast-2:893445519708:uyue0zqh15/null/GET/\"}}"}
    AuthorizerConfigurationException

Why doesn't the authorizer like the JSON response?

Answer 1

I just ran into the same error but in my case the problem was that context was too complex - apparently it cannot contain array or object-valued keys.

This is documented here: https://docs.aws.amazon.com/apigateway/latest/developerguide/api-gateway-lambda-authorizer-output.html

Notice that you cannot set a JSON object or array as a valid value of any key in the context map.

(I was trying to set a decoded JWT as the context, which has an array-valued roles key. I'm now sending the encoded JWT instead)