TypeError a bytes-like object is required, not 'str'

[llybin]

voximplant/apiclient/client.py in add_user at line 1743

if user_custom_data is not None:
    params['user_custom_data']=user_custom_data

res = self._perform_request('AddUser', params)
if "error" in res:  <---- TypeError a bytes-like object is required, not 'str'
    raise VoximplantException(res["error"]["msg"], res["error"]["code"])

return res

def _perform_request(self, cmd, args):
    params = args.copy()
    params["cmd"] = cmd
    headers={'Authorization': self.build_auth_header()}
    result = requests.post("https://{}/platform_api".format(self.endpoint), data=params, headers=headers)
    if result.headers.get("content-type","").split(";")[0].lower() == "application/json":
        return json.loads(result.text)
    else:
        return result.content   <------ not dict here on server error for example

[llybin]

POST https://api-node3.voximplant.com/platform_api [502]
{
reason: Bad Gateway
}