I have an API Gateway that is one of many origins behind a CloudFront distribution that I created. I am trying to forward certain headers to origins (Host, Origin, among others). When I do not forward any headers, the requests reach the API Gateway just fine. However, as soon as I enable header forwarding in the CloudFront distribution (either All or Whitelist) the API Gateway is no longer able to handle the requests. I get the following error:

Any advice on fixing this problem?

As commented above, you can’t forward the Host header to the API Gateway origin. Without the Host header, API Gateway doesn’t know what API is being invoked.