Symptom

As I click Generate SDK in SDK Generation tab under API Gateway, I always encounter 500 error in screenshot below.

I found the issue could be reproduced after I define 204 in Method Response below.

After contacting AWS support and API Gateway team, they have indicated that while you can have/deploy an API with multiple 2XX responses, the SDK generation only supports a single 2xx response.

AWS team have therefore opened this as a feature request (refer to BPL-4495) and has been added to their backlog.