You set up your Facebook App incorrectly. Go back to the app and double check the URL you put in for the site, and make sure it’s exactly correct. Caps matters. Lack or presense of www matters. That sort of thing.
Same issue here….
*Goes away to look for answer*
Found this and it worked for me hooray!
From the Facebook development page “Apps-YourAppName”, click on Basic in the LEFT Nav.
There are 3 sections on this page: Basic Info, Cloud Services, and “Select how your app integrates with Facebook”
In the Select how your app integrates with Facebook section, select “Website”
Enter your fully qualified domain name in the Site URL dialog box. Example: http://www.mydomain.com OR http://mydomain.com (my site does not include the www so I didn’t add it).
At the bottom of the page click the “Save Changes” button. You may receive a notice that it may take several minutes to blah blah blah….but you can continue with the next steps immediately.
Now, in the Basic Information section at the top of this screen, you can now add your App Domain. This should be formatted as mydomain.com. Do not add “http://” and do not add “/” at the end of the domain name.
NOTE: My site does not use the www, so I cannot confirm that it’s required in Step #6. Try it both ways if you’re unsure.
At the bottom of the page click the “Save Changes” button. You may receive a notice that it may take several minutes to blah blah blah….but you can continue with the next steps immediately.
At this point the error was NOT displayed as it was before.
Source: http://stackoverflow.com/questions/9330690/facebook-error-app-domain-is-not-a-valid-domain
Thanks Otto and Stuart working on it now !!!
Thanks Samuel Wood (Otto)
