Hello Devin!

This issue has appeared recently due to a new safety policy on FB. Now "Use Strict Mode for Redirect URIs and Enforce HTTPS" enabled by default and can no longer be disabled, see details for example here https://developers.facebook.com/bugs/518422995172099/. So, to fix your Facebook app you need to do following actions:

1) login to http://developers.facebook.com/apps/ and find app which you need to fix,

2) click "+ Add Product" link,

3) choose "Select Facebook login" as a product,

4) choose "Web" as the "Platform",

5) enter your UNA site URL and press the "Save" button,

6) then click on the "Continue" button till the Step 5,

7) find on the left side point "Facebook Login" and click "Settings" menu within,

8) under Client oAuth settings, make sure "Use Strict Mode for Redirect URIs" parameter is set to "No" and that your site URL is in the Valid OAuth redirect URIsbox. Then the press "Save" button.

9) Check this changes in action.

With the best regards, Leonid