Facebook application development Fatal error: Uncaught OAuthException: An active access token must be used

This Topic aplies to SDK 3.x
Subject ( Fatal error: Uncaught OAuthException: An active access token must be used )
The Answer to this problem could be found here : Link
But let's discuss it, shall we!
- There are 4 reasons why Tokens get expire :

1. The token expires after expiration time (2 hours is the default).
2. The user changes his/her password which invalidates the access token.
3. The user DE-authorizes your app.
4. The user logs out of Facebook.

I will not explain the 4 reasons but i will just post the script solution :
- If there is any question, just post a comment.
- i will get back here to try to explain the codes .

google me (evry1falls)