Extending Facebook Page Access Token - facebook

Question

i need to extend my facebook access token, I'm calling this:
https://graph.facebook.com/oauth/access_token?
client_id={MY PAGE ID}&
client_secret={THE SECRET KEY OF MY APP}&
grant_type=fb_exchange_token&
fb_exchange_token={AN ACCESS TOKEN FOR MY PAGE}
and I'm getting this error:
"error": {
"message": "Error validating application. Cannot get application info due to a system error.",
"type": "OAuthException",
"code": 101
}
I've seen a lot of problem with that access_token, but none answer relative to pages, idk why facebook use api that why... but is the way...
Thank you,

Answer 1

To get a long-lived access token you need to follow those steps:
Create an Application
Create a Page (your account need to be "administrator" of the page)
Associate the application to the Page (the same way you do it when you want to add a Page Tab to a Page)
http://facebook.com/add.php?api_key=*YOUR_APP_ID*&pages=1&page=*YOUR_PAGE_ID*
Get a short-lived access token with the permission "manage_pages" associated to your Application.
https://graph.facebook.com/oauth/authorize?client_id=__APP_ID__&scope=manage_pages&redirect_uri=http://www.facebook.com/connect/login_success.html
then
https://graph.facebook.com/oauth/access_token?client_id=__APP_ID__&redirect_uri=http://www.facebook.com/connect/login_success.html&client_secret=__APP_SECRET__&code=__CODE_FROM_PREVIOUS_REQUEST__
Using the Graph API Explorer with the request /me/accounts you can see the access tokens for each Pages that you are administrator. The problem is that those access token are short-lived.
Convert your short-lived access token to a long-lived (extending 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=_ACCESS_TOKEN_ON_STEP_4_
You can now test your new access token with the Access Token Debugger.

Answer 2

Scenario 5: Page Access Tokens
When a user grants an app the manage_pages permission, the app is able
to obtain page access tokens for pages that the user administers by
querying the [User ID]/accounts Graph API endpoint. With the migration
enabled, when using a short-lived user access token to query this
endpoint, the page access tokens obtained are short-lived as well.
Exchange the short-lived user access token for a long-lived access
token using the endpoint and steps explained earlier. By using a
long-lived user access token, querying the [User ID]/accounts endpoint
will now provide page access tokens that do not expire for pages that
a user manages. This will also apply when querying with a non-expiring
user access token obtained through the deprecated offline_access
permission.
https://developers.facebook.com/roadmap/offline-access-removal/