# Handling Lambda errors with an API Gateway API
<a name="services-apigateway-errors"></a>

API Gateway treats all invocation and function errors as internal errors. If the Lambda API rejects the invocation request, API Gateway returns a 500 error code. If the function runs but returns an error, or returns a response in the wrong format, API Gateway returns a 502. In both cases, the body of the response from API Gateway is `{"message": "Internal server error"}`.

**Note**  
API Gateway does not retry any Lambda invocations. If Lambda returns an error, API Gateway returns an error response to the client.

The following example shows an X-Ray trace map for a request that resulted in a function error and a 502 from API Gateway. The client receives the generic error message.

![\[\]](http://docs.aws.amazon.com/lambda/latest/dg/images/tracemap-apig-502.png)


To customize the error response, you must catch errors in your code and format a response in the required format.

**Example [index.mjs](https://github.com/awsdocs/aws-lambda-developer-guide/tree/main/sample-apps/nodejs-apig/function/index.mjs) – Error formatting**  

```
var formatError = function(error){
  var response = {
    "statusCode": error.statusCode,
    "headers": {
      "Content-Type": "text/plain",
      "x-amzn-ErrorType": error.code
    },
    "isBase64Encoded": false,
    "body": error.code + ": " + error.message
  }
  return response
}
```

API Gateway converts this response into an HTTP error with a custom status code and body. In the trace map, the function node is green because it handled the error.

![\[\]](http://docs.aws.amazon.com/lambda/latest/dg/images/tracemap-apig-404.png)