I used your exact payload with one minor change to use a cart id that is valid for the company id I was making the POST request to, and did not receive an error.
I would suggest ensuring you are sending the JSON payload to the url as expected.
I used your exact payload with one minor change to use a cart id that is valid for the company id I was making the POST request to, and did not receive an error.
I would suggest ensuring you are sending the JSON payload to the url as expected.