Additional properties are not allowed. Unexpected property found in the input.

The "400 Bad Request" error with the message "Additional properties are not allowed ('functions' was unexpected) - 'messages.0'" in the Azure OpenAI API is likely due to several possible reasons:

Invalid Request Configuration

The request payload may contain properties that are not allowed or expected by the API. Specifically, the presence of a 'functions' property within the 'messages' array is unexpected and violates the API's schema requirements.

Incorrect Payload Structure

The structure of the payload, particularly the 'messages' array, may not conform to the expected format defined by the OpenAI API. This could include having additional or unexpected fields that are not recognized by the API.

API Schema Compliance

The request may be violating the specific schema or constraints defined by the OpenAI API, which does not allow certain properties like 'functions' in the context of the 'messages' array.

API Version and Endpoint Issues

There could be discrepancies between the API version or endpoint being used and the expectations of the API, leading to incompatible request structures.