Unexpected token % in JSON at position 0","code":"1630

[Plucky]

Im trying to request a access token and Im receiving the following error message.

{"messages":[{"message":"Unexpected token % in JSON at position 0","code":"1630"}],"response":{}}

Its just a test database hosted on a windows server v19 and Im connecting via a Prepress workflow Server that has a 'Interact with Web Service' module

I can retrieve a list of hosted files but as soon as I change to a POST method and supply Authorization it errors. I've checked the u/p and that's correct.

Ive tried different variations of suppling the login details and all comeback with same error. The response from the GET hosted files:

 {"response":{"databases":[{"name":"ESKO"}]},"messages":[{"code":"0","message":"OK"}]}. Any ideas what Im doing wrong?