# Raising Exceptions from Lambda to API Gateway Caller > [!META]- Inline Metadata > [status:: boat] > [source::] > [tags:: #note/evergreen #state/boat #concepts/aws/lambda #concepts/aws/api-gateway ] > [up:: [[AWS Lambda MOC]] [[AWS API Gateway MOC]]] You can send exception feedback from a Lambda to an API Gateway API either by raising a Python exception and handling it via a mapping template, or return a specific set of values from the main handler function. ## Returning from the Handler Function You can return a dictionary that includes at least: - the desired status code - the message body (JSONified) - and whether or not the body is base64 encoded ```python return { "statusCode": 404, "body": simplejson.dumps( f"User {username} not found" ), "isBase64Encoded": False, } ``` ## Raising an Exceptions Using a [mapping template](https://aws.amazon.com/blogs/compute/error-handling-patterns-in-amazon-api-gateway-and-aws-lambda/) allows you to simply use regex to associate an error message from a plain Python exception with a certain HTTP code. I don't have any examples because I haven't done it, preferring the [[Raising Exceptions from Lambda to API Gateway Caller#Returning from the Handler Function|previous method]].