title: AWS Lambda calling API gateway getting 500 internal server error
body: <p>I'm developing several AWS serverless applications using Lambda and API gateway.</p>
  <p>At one point, I tried to execute an API request on one application (using requests python lib) from code running inside a Lambda function in another application. I get 500 server error. From the logs it appears that the Lambda function behind the API gateway is not starting at all. I don't find any logs that can tell me what happened.</p>
  <p>Additional details:</p>
  <ul>
  <li>The API gateway is protected by IAM auth.</li>
  <li>The calling lambda has permission to &quot;execute_api&quot;</li>
  <li>The request is signed according to Signature V4 - I followed the example here: <a href="https://docs.aws.amazon.com/general/latest/gr/sigv4-signed-request-examples.html#sig-v4-examples-post" rel="nofollow noreferrer">https://docs.aws.amazon.com/general/latest/gr/sigv4-signed-request-examples.html#sig-v4-examples-post</a> .</li>
  </ul>