i am trying to add this script to my iframe app on facebook but it seems not to work:
$signed_request = $facebook->getSignedRequest();
$like_status =
Unfortunately, I had the same issue. After hours and hours trying to solve it, I finally created a new application, with exactly the same set up. I updated key and secret in my code to the new ones and voilà - its running like a charm from the first attempt.
Definitly a Facebook issue. Maybe resetting App ID and secret could also had worked, but I didn't try that first.