Facebook Graph: unable to get group feed

I'm trying to get the group feed via Facebook Graph API.

According to the documentation

https://developers.facebook.com/docs/graph-api/reference/v2.8/group/feed

I'm trying to costruct the appropiate url and here it is

https://graph.facebook.com/v2.8/154205721275156/feed?access_token=[TOKEN]

And each and every time I'm getting the next result

{ "error": {

"message": "An unknown error has occurred.",
  "type": "OAuthException",
  "code": 1,
  "fbtrace_id": "B7/12QU7BW/"

} }

[TOKEN] is valid, it applies to the member of the group.

At the same time other requests for the same group, such as "/events" or "/members", return correct answers.

What is wrong with the "/feed" request?