I'm working on Rails app using Facebook Graph everything was working fine and then suddenly images stop loading for user_pages, i debug and found the following error,
{ "error": { "message": "The 'manage_pages' permission must be granted before impersonating a user's page.", "type": "OAuthException", "code": 190 } }
Any idea why it start happening. Please see attached screen-shot 
Thanks
30th April was the last date when Facebook stopped supporting older versions of the App. I am not 100% sure but it seems you need to go to your developer account and submit a review request for your app with additional permissions.