Getting an error with XMLHttpRequest and not sure what to do.

I have been banging my head against this for a few days and am not sure what I am doing wrong or what I should be doing differently. I am trying to hit an API endpoint via post. I can hit the endpoint just fine when I use postman (with interceptor so I can set my origin header). Postman is using a total of 3 headers and 2 parameters.As soon as I move to code I am running into the following error (found in responseText) on readyState 3, {"error":"server_error","error_description":"Unable to deserialize token envelope."} with a status of 400.I have other requests to different end points that are working just fine (granted they are all gets). I don't know if this is a post problem or something else. Any advice on anything I can try to change or code I can put in to help debug?Sorry if this is the wrong sub for this.If I intentionally break a parameter I get a response that I am missing a parameter, which I would expect. So

Submitted September 22, 2017 at 10:19PM by azazael13