Earlier i was searching for groups with a particular keyword on facebook using - https://graph.facebook.com/search?q=query&type=group&access_token=abcd..
Since last month it has stopped working. This search now returns always for any keyword an empty data array. While for types page,user,event,post still returns proper results. This happened by the time versioning was introduced. I tested also with the Graph API Explorer with different versions and none worked. You can check it from here: https://developers.facebook.com/tools/explorer/