CORS stopped working when upgrading from V2 to V3

Serverless Framework
1

We are trying to upgrade from V2 to V3 and we started getting CORS errors from our API Gateway. Looking over the documentation for “advanced usage” we have everything correct.

  events:
    - http:
        path: /authentication/referrer/validate
        method: get
        cors:
          origin: '*'
          headers:
            - Authorization
            - Content-Type
            - X-Api-Key
            - X-Amz-Date
            - X-Amz-Security-Token
            - X-Amz-User-Agent
            - x-auth-token
            - x-referrer-token
            - Cache-Control
            - Pragma
          allowCredentials: false
        private: false

We aren’t getting any errors, but we noticed that the Cache-Control and Pragma headers weren’t showing up on our API Gateway either.

I tried to check if this was something that changed in V3 but the link for full changes seems to have been removed. https://www.serverless.com/framework/docs/guides/upgrading-v3

Does anybody know how to resolve my CORS errors and/or where to find the full V3 notes?

2

@daynesuke I would recommend looking at the logs for your Lambda function. Usually when what you describe happens this is because the Lambda is returning a 5XX error code and the automated CORS implementation does not support that HTTP status code. Therefore, your browser receives a CORS error and not the error from the failed Lambda. Once your Lambda stops returning errors and actually returns the result from the Lambda function itself the CORS should stop.