Invalid chat format: missing required 'url' field in image_url dictionary.

The error "Invalid chat format. Expected 'url' field in image_url dict" with a 400 status code in the OpenAI API is likely occurring because the API is expecting a specific format for image data that is not being met. Here are the key reasons:

Incorrect Payload Structure

• The API expects content blocks to be either of type text or image_url, but the current payload structure does not match this expectation. Specifically, when using an image_url type, it requires a url field within the image_url dictionary, which is missing in your request.

Incompatibility with Base64 Encoded Images

• If you are trying to use base64 encoded image data, the API might not be configured to accept it in the current format. The error suggests that the API is looking for a URL, indicating that base64 encoded images may not be supported in the way you are attempting to use them.

Model Specific Requirements

• Different models, such as the gpt-4-vision model, may have specific requirements for how image data should be provided, and the current request does not align with these requirements.