Why does /USER_ID/feed return an unspecified error?

Few days ago, I noticed my application stopped working. After some debugging I found there's a problem in call to /USER_ID/feed (including access token, of course)

I found nothing like deprecation notice or bug report about this one. I've tried the /USER_ID/feed connection through explorer and it gave me the same error

{
  "error": {
    "message": "An unknown error has occurred.", 
    "type": "OAuthException", 
    "code": 1
  }
}

Is there something I missed or is it just Facebook's problem/bug?

Solution

It has probably been some kind of a bug, because it's everything working again without any notice.