The error message 'role' is a required property - 'messages.1' with a 400 status code in the OpenAI API indicates that the request is missing a required role property in one of the messages sent in the API request.

Here are the key reasons for this error:

• Missing or Incorrect Role: The API expects each message to have a role property (e.g., user, assistant, function) which is not provided or is incorrect in the request.

• Invalid Request Structure: The structure of the request, specifically the messages array, is not correctly formatted according to the API's requirements. This could be due to missing or misconfigured properties within the messages.

This error suggests that the server cannot process the request because it lacks the necessary information to understand the roles of the messages being sent.