When you schedule a posts on FBGAPP, in some rare cases, the scheduled posts might hit a hard rock on the way due to some reasons, and among the common reasons for a scheduled post to stop running is the ‘Invalid Access Token‘ error.
How to Detect this Error
FBGAPP comes with a Logging feature that stores all of the errors encountered during a scheduled post. And to locate the error log, you need to Navigate to Posts > Scheduled Posts > And Click the Folder Icon at the right-hand side of the displayed table.
In the Log page, you will see the reason why your scheduled posts stopped running and if the error message seen is Invalid Access Token as shown in the image above, then read below to see how to fix;
How to Fix Invalid Access Token Error
The invalid access token error simply means the token for the selected app used for posting is expired and needs to be re-authenticated.
And to fix, all you need to do is Re-authenticate the current app used for posting.
To Re-authenticate, Goto Settings > Facebook Apps > Deauthenticate the App. And then click the Authenticate button again.
When you click the Authenticate button again, you do NOT need to go through all of the procedures as you would when Authenticating for the first time. Rather, all you need to click is the Get App Authenticate Link (As shown in the image below).
Copy the displayed access token from the next window that displays and then paste in the Access Token Box. Click the Test Access Token to ensure the copied token is valid, then click the Set Access Token Button.
You have successfully re-authenticate your app. Now is time for you to resume the paused schedule or schedule a new post using your authenticated app.