Input is not of type 'string'. Please ensure that the input is a valid string for processing.

The 400 Bad Request error in the OpenAI API is likely occurring due to several possible reasons:

Invalid Request Syntax or Configuration

The request may contain invalid syntax or configuration, such as incorrect API keys, expired API keys, or improperly formatted JSON payloads. The server is unable to understand the request due to these issues[2)[5.).

Incorrect Data Type

The error message indicates that the data provided ({'paragraphs': [...]}) is not of the expected type, specifically that it is not a string. The API likely expects a string or a different data structure that matches its requirements.

Rate Limiting and Throttling

The API might be rate-limited or throttled, meaning the number of requests made within a certain time frame exceeds the allowed limits, leading to a 400 error.

Improper HTTP Library Usage

The error could be due to the incorrect usage of the HTTP library, resulting in an invalid JSON payload being sent to the server.

Server-Side Issues

There might be server-side issues or changes in the API, such as changes in token counting or other backend configurations, which can cause intermittent 400 errors.