My web-app has the Facebook JS SDK implemented.
Yesterday, everything was working fine and without any modification on the code, the script request started to return
I figured this one out.. it seems the .net isn't working anymore.. I used ".com" instead:
Use https://connect.facebook.com/en_US/sdk.js
instead of https://connect.facebook.net/en_US/sdk.js
It is related to this bug, subscribe to get updated: https://developers.facebook.com/bugs/949091578557056/
There is a workaround to use .com instead of .net.
Edit: The bug is fixed now.
I had the same problem. Use //connect.facebook.com/en_US/sdk.js url.