AWS Lambda binary response not working properly

Serverless Framework
,
1

I’m having an issue with AWS API gateway + Lambda binary responses. I have setup my configuration through serverless. I’m pretty sure I’ve tried everything I could and skimmed most of the documentation of AWS and serverless but I can’t seem to figure it out. Some help would be appreciated.

When calling the associated gateway url I see all actions performed properly up until the response callback. When arriving at the callback the lambda times out and I get a 500 response from the API Gateway with the following content: “message”: “Internal server error” . As seen in the serverless.yml config I’ve upped the timeout to make sure it isn’t a timing issue. The base64 string is never larger than 100kb

Node callback code

 callback(null, {
   statusCode: 200,
   headers: {
     "Content-Type": "image/png"
   },
   body: buffer.toString('base64'),
   isBase64Encoded: true
 })

Serverless config

provider:
  name: aws
  runtime: nodejs12.x
  region: eu-central-1
  lambdaHashingVersion: 20201221
  logs:
    restApi: true
  timeout: 20
  apiGateway:
    binaryMediaTypes:
      - 'image/png'

functions:
  lazy:
    handler: handler.lazy
    vpc:
      securityGroupIds:
        - xxx
      subnetIds:
        - xxx
    events:
      - http:
          method: get
          path: xxx
          response:
            contentHandling: CONVERT_TO_BINARY