Unsupported get request in Facebook Graph API

This error occur due to several problem in permissions of your page

1. go to edit page ->manage permission

check Age restrictions : 13+

2. go to basic information -> Start Type:: set to launched

I had also encountered this problem, and it was because the Facebook page I was managing had "County Restrictions" set in the Manage Permissions menu. Once I removed this restriction, the graph error went away.