This article explains how to re-authorize / reconnect a Facebook page.
This will need to be performed whenever the following occurs:

• The user that connected the Facebook channel changes their password.
• The user is no longer a Page Admin (Another Page Admin will need to reconnect)
• You are unable to publish to a Facebook Page and see the following message(s):

App [FB_APP_NAME] is not valid: Error validating access token: The session has been invalidated because the user changed their password or Facebook has changed the session for security reasons.

What to do

Before we begin, ensure that you have already logged into the Facebook using the user account that has Page Admin rights on the intended Fan page you need to reconnect.

1. Login to the platform, click the Settings icon and open % Manage Channels.
2. Select the channel that needs to be reconnected in the left-hand menu.
3. At the bottom under Administration, click ± Reconnect.
4. A list of all Facebook pages you are a Page Admin for will appear, click connect on the correct Facebook page.
   If you're only a Page Admin for one page you will not be shown a list, it will instead auto-select the only valid page.
5. A green success message should appear and your page should now be connected.