I am the administrator of a Facebook Page. I am building a web app which, under certain circumstances, will post on Facebook as that Page.
With most APIs, I would just get an API key, and supply that when connecting to the API from my app. But Facebook expects an access token instead of an API key. (Specifically, in this case, it needs a "page access token".)
I am trying to figure out how to get a page access token that will be as permanent as possible.
After jumping through a bunch of esoteric, undocumented hoops (see here and here) in order to get a token that wouldn't expire, I had this working. When I ran the token through Facebook's Access Token Debugger, the "Expires" field read "Never". All was good in the world.
But, the next day, my token became invalid anyway. The Access Token Debugger, and my app's calls to Facebook's PHP SDK, both started returning this error:
Error validating access token: Session does not match current stored session. This may be because the user changed the password since the time the session was created or Facebook has changed the session for security reasons.
It seems that a token can become invalid for a variety of reasons (but this article is five years old, so who knows – Facebook changes things every two weeks). I had not changed my password. (I might have logged out of Facebook, though.) Facebook offers no specifics about why this particular token might have become invalid.
I've also seen a few references to a permission called offline_access, but Facebook seems to have removed this.
I suppose my question is twofold:
In general, I've found Facebook token authentication to be incredibly brittle when calling the Facebook API from the server. The token system seems to be designed mainly to allow other users to grant (or revoke) various kinds of account access to my apps. But that's not what I'm doing – I'm trying to get a token that will let me post to a page that I own. And for that scenario, Facebook's aggressive invalidation of tokens becomes a serious liability. I can't launch my app if my access token (and therefore my Facebook integration) could randomly stop working at any moment, requiring me to generate a new token and update the app. This seems absurd. Is there an alternative method of authenticating to Facebook for my purposes?
If a page access token is, in fact, the best way to authenticate my app to Facebook in order to post as my Page: how can I ensure that my token doesn't spontaneously become invalid?
I hate developing for Facebook :/ Thanks for any insight you can offer.
Extended Page Tokens are valid forever. They only get invalidated if you change your password or if you change the App Secret of your App. There´s really no magic in it, checking if the Token is still valid is obviously not a bad idea but that´s up to you. For example, you can send yourself an automated Email when there is an error using the Token, so you can refresh it. But it will really just happen if you change your password.
Links:
https://developers.facebook.com/docs/facebook-login/access-tokens
http://www.devils-heaven.com/facebook-access-tokens/
Related
Should the limited login store the access token for future session?
I'm transferring my iOS app from classic login to limited login. But I can't get the auto-re-login to work.
Re-login with classic works correctly as docs says. "The FBSDKLoginManager sets this token for you and when it sets currentAccessToken it also automatically writes it to a keychain cache." The app r-logins correctly.
But with limited login it seems it doesn't store the token. Should is store? The docs are unclear whether limited login should do this or not.
Best, Hu
Let's start with some points to proceed:
Limited Login mode doesn't provide you an Access Token. It provides you an Authentication Token. It's a regular JWT you can parse, but you are not able to use it for FB Graph API requests;
You can get the basic information about the user just by decoding this Authentication Token or using FB SDK right after signing in;
Currently, this token has an expiration of 1 hour, but you don't really need to refresh it every hour unless you need to get an update of the user information (for instance, to fetch a changed name, email, or a list of friends);
As you can see in the official blog post of Facebook, to refresh a token with information inside it, you need to re-authenticate a user, so call an SDK method to show FB popup. Reference: FB: Announcing expanded functionality in Limited Login
Currently, the official documentation is really unclear and has just a couple of pages related to the Limited Login mode. So if you still have any other questions, feel free to ask, I'll update the post.
when I do a get request to
https://graph.facebook.com/[userid]
with the access_token i get all the basic info
but when I do
https://graph.facebook.com/me
with the same token i get an error message: An active access token must be used to query information about the current user
I have tried to under stand what can cause that.
I even tried to token that comes with the signed request
I'm on classic asp, with JSON library, I want the auto to be server side if possible. the FB.api("/me" is working but it is not what i really want to achive
I am pretty sure you don´t have a user access token. Did you login the user? Of course you get the public data of every user with your first link, even without any access token. You can even put it directly in the browser and will get results. But for "/me" you have to authorize the user to your app.
See here: https://developers.facebook.com/docs/howtos/login/server-side-login/
It is the same problem as in the other thread for sure, just a different Programming language.
Remember: If the user did not accept at least the basic permissions in a dialog or redirect, he is not logged in and you will never know anything about him in the app (except for some specifics in tab apps, like language, like-status and stuff).
I have an application that used to use offline_access, which obviously needs changing since that's going away.
We use this permission to publish messages to the facebook wall of a user when they interact without our backend through any number of APIs. We have a website, several mobile applications on iPhone, Android, Blackberry, and Nokia phones that connect to the application, as well as a desktop application that interfaces with hardware devices and all of these can cause the backend to attempt to publish to facebook, but only the website allows the user to make the initial authorization with facebook.
From what I understand, using server-side authentication gets 60 day long tokens, and the only way to get new tokens is to redo the authentication process which assuming the user hasn't changed password, is logged into facebook, and hasn't de-authorized the application will appear as nothing but a series of automated redirects.
Is there any other way to do this? For example, what exactly does fb_exchange_token do? Is it applicable in this case or does this ONLY apply to tokens received via the javascript API?
Is there anything we can do for these non-website user interfaces aside from incorporate the native facebook APIs and do the same thing for as the website?
Attempting to use fb_extend_token was pretty fruitless. Rerunning the standard authentication returned the same token but with a fresh 60 day expiry time. Doing it again a short while later didn't extend the token. I'm hoping this means I can only do this once a day, not once per token.
Since I was using the server-side flow and the keys would never be seen by the user I was able to rework my app slightly to use my APPLICATION token. These keys belong to your app and allow you to use the API on behalf of a user for as long as they haven't revoked their permission. The user authorization tokens can expire, but as long as the user hasn't explicitly removed your app from the apps they've allowed, your token will continue to allow you to post to the wall using a /user/ URL, the /me/ URLs won't work because your token is bound to your app.
I believe once the deprecation of offline_access is complete, obtaining/exchanging access tokens is the only way to do what you need.
Anyone who had offline access before the deprecation will still be able to use your application normally, for 60 days at least. Once this period is over, you have to re authorize users and extend their access tokens for another 60 days. To do this you have them log in, and authorize your app (if necessary). Then you extend their access token using fb_exchange_token, so it is good for 60 days.
I'm sure you have seen it, but it's all outlined in this article, more specifically the section about previously using offline_access. I also found this post useful for doing an upgrade. Here is another link that further details how to deal with invalid tokens.
EDIT from #avs099: I'm starting the bounty on this post as I have exactly the same issue. I summarize the problem here, and leave the post itself without any changes at the bottom for the reference.
What we have: Facebook page access token, obtained as described here: Authenticating as a Page and which live was extended to 60 days with new fb_exchange_token request.
What is the problem: this token works for some time - sometimes I can post hundreds of photos to my fan page in the period of several days; sometimes it's literally few photos - and then I start getting either
(OAuthException) Error invalidating access token: The session has been
invalidated because the user has changed the password.
or
(OAuthException) Error invalidating access token: Session does not
match current stored session. This may be because the user changed the
password since the time the session was created or Facebook has
changed the session for security reasons.
exceptions from the Facebook - but of course I did not do change password or deauthorized the app.
Additional information: Not sure if that matters but:
Sometimes I start using token few days after I request it from the Facebook
Token is requested (by the C# backend) from the server
which is located in a different geographical region from the desktop
app which posts photos to the fan page.
It happens sometime that several different desktop apps post photos from different PCs (i.e. different IPs I guess)
Anybody has a clue what's going on and how to resolve this?
Thank you.
I have a facebook app that serves two purposes:
1) Allows users to facebook connect with my site
2) Allows my site to post to my sites facebook fan page wall
What I'm concerned about is the 2nd usage. I used to be able to set the permissions for an app on a fan page to just allow posting (via the php sdk) without any concern about an access token. Now I've created some new fan pages and that functionality seems to have been removed. Alright, so I go through the whole process of getting an access token (successfully) for the user (always me or another admin of my facebook fan pages) and use that token to get the access tokens for the fan pages I manage (I have the manage_pages permission and so do the other admins for the pages I want to post to). However by the engine gets around to posting content to my fan pages the tokens have expired with one of two error messages:
Error invalidating access token: Session does not match current stored session. This may be because the user changed the password since the time the session was created or Facebook has changed the session for security reasons.
or
OAuthException: Error invalidating access token: The session has been invalidated because the user has changed the password.
But this isn't an access token dependent on outside users, only internal people (me and one other guy right now). We aren't changing our passwords or doing anything. I've even tested it by logging out of facebook after acquiring tokens and it works fine. It's just after a little while they expire for no reason that I can determine. When I get the tokens I can check them on the debugging tool and they are supposed to last 60 days (according to the doc) although the tool says they never expire.
I've set up the system so when it fails to post to the page I get an email with the link to my site to update the tokens.
Anyone have a clue what's going on?
As Mikhail pointed out, if you get an error reporting that the token is invalid cause user has changed the password. Odds are you are requesting a new token somewhere hidden in the code, when you already have a valid one.
Possibly related to this bug? https://developers.facebook.com/bugs/241373692605971?browse=search_4fb4832bcaf7b1549293950
I have the same problem in my app - sometimes tokens expiring.
One of the find reason: sometimes my app ask for new token while old token is valid and FB return an error or i couldn't save new token for some reason.
After that old token expire - only one token for pair user-app may be valid.
You can fetch the unauthorized token so a new token is requested (or whatever you like).
I can provide a nice explanation but you can read it all here:
https://developers.facebook.com/blog/post/2011/05/13/how-to--handle-expired-access-tokens/
A temporary solution is to ask the user to delete the application from it's profile, and allow it again.
I had same problem and resolved it "reinstalling the app to users facebook applications". it may help you if nothing answers to problem.
To do that:
facebook user who is facing the problem goes to its facebook page
he/she removes your app from his/her application list.
Retry to login via facebook sdk on android.
I am playing around with the Oauth 2.0 authorization in Facebook and was wondering if the access tokens Facebook passes out ever expire. If so, is there a way to request a long-life access token?
After digging around a bit, i found this. It seems to be the answer:
Updated (11/April/2018)
The token will expire after about 60 days.
The token will be refreshed once per day, for up to 90 days, when the person using your app makes a request to Facebook's servers.
All access tokens need to be renewed every 90 days with the consent of the person using your app.
Facebook change announce (10/04/2018)
Facebook updated token expiration page (10/04/2018)
offline_access:
Enables your application to perform authorized requests on behalf of the user at any time. By default, most access tokens expire after a short time period to ensure applications only make requests on behalf of the user when the are actively using the application. This permission makes the access token returned by our OAuth endpoint long-lived.
Its a permission value requested.
http://developers.facebook.com/docs/authentication/permissions
UPDATE
offline_access permission has been removed a while ago.
https://developers.facebook.com/docs/roadmap/completed-changes/offline-access-removal/
Try this may be it will help full for you
https://graph.facebook.com/oauth/authorize?
client_id=127605460617602&
scope=offline_access,read_stream,user_photos,user_videos,publish_stream&
redirect_uri=http://www.example.com/
To get lifetime Access Token you have to use scope=offline_access
Meaning of scope=offline_access is that :-
Enables your application to perform authorized requests on behalf of
the user at any time. By default, most access tokens expire after a
short time period to ensure applications only make requests on behalf
of the user when the are actively using the application. This
permission makes the access token returned by our OAuth endpoint
long-lived.
But according to facebook future upgradation the offline_acees functionality will be deprecated for forever from the 3rd October, 2012.
and the user will be given 60 days long-lived access token and before expiration of the access token Facebook will notify or you can get your custom notification functionality fetching the expiration value from the Facebook Api..
Note that Facebook is now deprecating the offline_access permission in favor of tokens for which you can request an "upgrade" to the expiry. I'm just now dealing with this, myself, so I don't have much more to say, but this doc may help:
https://developers.facebook.com/docs/offline-access-deprecation/
I came here with the same question as the OP, but the answers suggesting the use of offline_access are raising red flags for me.
Security-wise, getting offline access to a user's Facebook account is qualitatively different and far more powerful than just using Facebook for single sign on, and should not be used lightly (unless you really need it). When a user grants this permission, "the application" can examine the user's account from anywhere at any time. I put "the application" in quotes because it's actually any tool that has the credentials -- you could script up a whole suite of tools that have nothing to do with the web server that can access whatever info the user has agreed to share to those credentials.
I would not use this feature to work around a short token lifetime; that's not its intended purpose. Indeed, token lifetime itself is a security feature. I'm still looking for details about the proper usage of these tokens (Can I persist them? How do/should I secure them? Does Facebook embed the OAuth 2.0 "refresh token" inside the main one? If not, where is it and/or how do I refresh?), but I'm pretty sure offline_access isn't the right way.
Yes, they do expire. There is an 'expires' value that is passed along with the 'access_token', and from what I can tell it's about 2 hours. I've been searching, but I don't see a way to request a longer expiration time.
since i had the same problem - see the excellent post on this topic from ben biddington, who clarified all this issues with the wrong token and the right type to send for the requests.
http://benbiddington.wordpress.com/2010/04/23/facebook-graph-api-getting-access-tokens/
You can always refresh the user's access token every time the user logs into your site through facebook.
The offline access can't guarantee you get a life-long time access token, the access token changes whenever the user revoke you application access or the user changes his/her password.
Quoted from facebook http://developers.facebook.com/docs/authentication/
Note: If the application has not requested offline_access permission, the access token is time-bounded. Time-bounded access token also get invalidated when the user logs out of Facebook. If the application has obtained offline_access permission from the user, the access token does not have an expiry. However it gets invalidated whenever the user changes his/her password.
Assume you store the user's facebook uid and access token in a users table in your database,every time the user clicks on the "Login with facebook" button, you check the login statususing facebook Javascript API, and then examine the connection status from the response,if the user has connected to your site, you can then update the access token in the table.
Hit this to exchange a short living access token for a long living/non expiring(pages) one:
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
log into facebook account and edit your application settings(account -> application setting ->additional permission of the application which use your account). uncheck the permission (Access my data when I'm not using the application(offline_access)). Then face will book issue a new token when you log in to the application.
Basic the facebook token expires about in a hour. But you can using 'exchange' token to get a long-lived token
https://developers.facebook.com/docs/facebook-login/access-tokens
GET /oauth/access_token?
grant_type=fb_exchange_token&
client_id={app-id}&
client_secret={app-secret}&
fb_exchange_token={short-lived-token}
This is a fair few years later, but the Facebook Graph API Explorer now has a little info symbol next to the access token that allows you to access the access token tool app, and extend the API token for a couple of months. Might be helpful during development.
check the following things when you interact with facebook graph api.
1) Application connect URL should be the base of your "redirect_uri"
connect URL:- www.x-minds.org/fb/connect/
redirect_uri - www.x-minds.org/fb/connect/redirect
2) Your "redirect_uri" should be same in the both case (when you request for a verification code and request for an access_token)
redirect_uri - www.x-minds.org/fb/connect/redirect
3) you should encode the the argument when you request for an access_token
4) shouldn't pass the argument (type=client_cred) when you request for an access_token. the authorization server will issue a token without session part. we can't use this token with "me" alias in graph api. This token will have length of (40) but a token with session part will have a length of(81).
An access token without session part will work with some cases
eg: -https://graph.facebook.com/?access_token=116122545078207|EyWJJYqrdgQgV1bfueck320z7MM.
But Graph API with "me" alias will work with only token with session part.
I don't know when exactly the tokens expire, but they do, otherwise there wouldn't be an option to give offline permissions.
Anyway, sometimes requiring the user to give offline permissions is an overkill. Depending on your needs, maybe it's enough that the token remains valid as long as the website is opened in the user's browser. For this there may be a simpler solution - relogging the user in periodically using an iframe: facebook auto re-login from cookie php
Worked for me...