Question

::UPDATE:: LINKS DO NOT EXIST ANYMORE!

Very strange indeed, this is definitely a bug! I did a test with app_id from another application and it worked.
See for yourself:

https://apps.megalopes.com/megabraziltv/test.php (app_id correct)

https://apps.megalopes.com/megabraziltv/test2.php (app_id from another application)

—/—

I found several people with the same question and all the answers are equal:
Site URL is not same as REQUEST_URI (Redirecting URL)

My app setting are:

Secure Page Tab URL: apps.megalopes.com/megabraziltv/…

App Domain: megalopes.com

code:

<div id="fb-root"></div>
      <script src="http://connect.facebook.net/pt_BR/all.js">
      </script>
      <script>
         FB.init({ 
            appId:'123456789', cookie:true, 
            status:true, xfbml:true 
         });

         FB.ui({ method: 'apprequests', 
            message: 'Here is a new Requests dialog...'});
      </script>

This simple code is not redirecting to any other url. I tested on the js console getting the same results. Sometimes works and sometimes I get this error message:

API Error Code: 191 API Error Description: The specified URL is not
owned by the application Error Message: redirect_uri is not owned by
the application.

Answer 1

Regardless of being page tab or canvas, you must identify the website Site URL in https://developers.facebook.com/apps

How I fixed:

App Domain: megalopes.com (domain)

Site URL: / Secure Canvas URL: / Secure Page Tab URL: https://www.megalopes.com (subdomain)