CAPCHA_NOT_READY - This is not an error, it means that the captcha has not been solved yet and you need to retry the request after 1-5 seconds
ERROR_WRONG_CAPTCHA_ID - The captcha ID of the solution you are trying to request does not exist
ERROR_CAPTCHA_UNSOLVABLE - Service could not solve the captcha
ERROR_BAD_REQUEST - Error in request, missing required parameter
ERROR_KEY_DOES_NOT_EXIST - You have entered an incorrect apikey, or you have run out of balance
All
Reference