Request to Yandex Directory API does not work. What could be the problem?

Question

API

Good day!
I ran into a problem when working with the Yandex Directory API , namely when working with commands.
There was a problem changing group settings .
For a given request (adding a team admin)

PATCH https://api.directory.yandex.net/v6/groups/20/ HTTP/1.1
User-Agent: Fiddler
Content-Type: application/json
Authorization: OAuth <токен>
Host: api.directory.yandex.net
Content-Length: 60

{"admins":[{"id":<id пользователя>},{"id":<id пользователя>}]}

I receive such a response from Yandex

HTTP/1.1 500 INTERNAL SERVER ERROR
Server: nginx
Date: Mon, 12 Mar 2018 09:00:54 GMT
Content-Type: application/json; charset=utf-8
Content-Length: 134
Connection: keep-alive
Keep-Alive: timeout=120
X-DC: SAS
X-Revision: 70
Etag: "70"
X-Request-ID: df165e88ba92739b10e47fe7c885b292
X-Response-Time: 0.265413999557
X-qloud-router: sas1-9db0931b86b1.qloud-c.yandex.net

{
    "message": "Unhandled exception: {error}", 
    "code": "unhandled_exception", 
    "params": {
        "error": "error"
    }
}

Please tell me how to solve the problem.
Has anyone experienced this or worked with this API?