I get error: "content not allowed in prolog" while trying to upload a csv file to the Netsuite file Cabinet

My question:
I get error: “content not allowed in prolog” while trying to upload a csv file to the Netsuite file Cabinet. What can I do to resolve that issue?

Details (like screenshots):


image

How I found the problem:
Setup Netsuite to gain access via token and specified the necessary parameters (cosumer key, token, etc.) and set the body to use “file”

I’ve already tried:
Changing he URL to use services from 2019 and 2022.
Here is the URL I am using in my request:
https://XXXXXXXXXX.suitetalk.api.netsuite.com/services/NetSuitePort_2021_1

Update:
Tried converting the CSV file to JSON… Same results