If you are using Facebook Login with MarketGrabber, Facebook may from time to time send out email messages requesting that you upgrade to a newer version of the Facebook Graph API.
To do this, login to developer.facebook.com.
Click on "My Apps". Select the app for your website.
In the Dashboard menu on the left click on settings.
Then click on Advanced Settings.
In the page that appears in the section "Upgrade API Version" select the latest version (2.10 as of the date this article was written).
Then press the Save Changes button on the bottom right part of the page.
You have now upgraded the Facebook API you are using with your site.