Currently I am using desktop windows service to download my Facebook page insights/ page likes/friends etc. graph data . so, for that i have added app on my facebook page an
To fix this you need to extend the short lived token.
You can also debug the access token without any user interaction to see if the action of extending the access token worked.
This link is a good reference about the expiration of offline access.
When you debug the access token using this url:
https://graph.facebook.com/debug_token?input_token=INPUT_TOKEN&access_token=ACCESS_TOKEN
INPUT_TOKEN is the user access token
ACCESS_TOKEN is the app access token which is formed like so: APP_ID|APP_SECRET
To clarify on that, If my app id is 123
& the app secret is abc
then the app access token is 123|abc
Simple solution just call following functions using PHP SDK
$facebook->setExtendedAccessToken();
and after it get extented access token through
$access_token = $facebook->getAccessToken();
OR
GET /oauth/access_token?
grant_type=fb_exchange_token&
client_id={app-id}&
client_secret={app-secret}&
fb_exchange_token={short-lived-token}