How to update a CRM user using Deluge scripting?

How to update a CRM user using Deluge scripting?

I am trying to update a CRM user (not a Contact, but an actual user of the CRM system) using the following Deluge snippet:
  1. zoho.crm.updateRecord("users", 438564385646, {"alias":"abc"});
However, I am getting the following error:
  1. {"code":"MANDATORY_NOT_FOUND","details":{"api_name":"users"},"message":"required field not found","status":"error"}
which required field is this complaining about? What is wrong in my code snippet?