CORS Issue - React form / API Gateway / Lambda function / nodejs - Execution failed due to configuration error

HI There,

My question is about CORS issue when I'm trying to connect a React form to lambda function through api gateway. The backend is setup using Terraform scripts.

The API endpoints respond fine when testing with Postman however it throws the below error when hitting the api endpoints from React form -

HTTP Method: OPTIONS, Resource Path: /register

Execution failed due to configuration error: No match for output mapping and no default output mapping configured. Endpoint Response Status Code: 200

Method completed with status: 500

I've spent tens of hours trying to fix this using various guidance from the web however to no avail. Therefore has anyone faced this issue before and how did this get resolved.