Get long live access token from Facebook
Solution 1:
There is a way to extend this to 60 days. described here: https://developers.facebook.com/docs/roadmap/completed-changes/offline-access-removal/
under Scenario 4: Client-side OAuth and Extending Access_Token Expiration Time through New Endpoint
Edit: In order to extend the access token you need to make the following request with your short lived access token:
https://graph.facebook.com/oauth/access_token?
client_id=APP_ID&
client_secret=APP_SECRET&
grant_type=fb_exchange_token&
fb_exchange_token=EXISTING_ACCESS_TOKEN
Solution 2:
Due to a bug in Facebook, some users will have to unauthorize the app before Facebook will issue the long-lived tokens.