http.post returns a "Illegal URL redirect" 

I am doing a POST request and the request fails:

"type":"error.SuiteScriptError","name":"ILLEGAL_URL_REDIRECT","message":"Illegal URL redirect"

Sample:

var headers = {};

headers['Content-Type'] = 'application/x-www-form-urlencoded';

headers['Pardot-Business-Unit-Id'] = objLogin.businessUnit;

headers['Authorization'] = 'Bearer ' + objLogin.access_token;

var URL = moduleSelection(value, objLogin);

var response = https.post({

url: URL,

headers: headers,

body: payload

});

This request works in Postman.

I have tested changing the redirect URL from app manager to a NS URL, that also fails.