How to add user using api

I am writing application for xibo.
My problem is to add user using API, it always return http 500 error.
Please someone advice me.
auth header is no problems,
endpoint: /api/user
Request method: POST
Content-Type: application/x-www-form-urlencoded

userName=test2_1746776248122&userTypeId=3&homePageId=1&password=********&groupId=1&newUserWizard=0&hideNavigation=0&email=test2%40oesf.jp

{“success”:false,“error”:500,“message”:“Unexpected Error, please contact support.”}
CMS-version 4.2.1