Solution :
To fix above error you need to make sure that your access token is currently active. Also please make sure you are in logged in condition. After this please try to clean the cookies and also your cache from your browser by using ctrl+shift+del.
If even after doing above steps you are still facing the error then in that case you must
check if you are getting 0 as the user id in return from your $facebook->getUser()
.Then you must also check your getAccessTokenFromCode()
from the base_facebook.php
and after that you must verify your access_token_response
format as there is the possibility of it may be in JSON format.
So you must try to use very appropriate decoding method to get your $response_params['access_token']
from $access_token_response
.
It will certainly help you.