How to fix Facebook app error "Incorrect Error: Can't Load URL: The domain of this URL isn't included in the app's domains"
Over the last 24 hours loads of developers have been having issues creating new Apps with Facebook.
It was confirmed on Facebook’s bug platform that they had made some changes to the the default settings for new Apps and now Strict Mode is automatically enabled for the oAuth settings. Strict mode means that when using Facebook login to connect your application or website to the App, the oAuth redirect URL has to be explicitly set, where as before it didn’t.
This is obviously part of a drive on their part to increase security, which is obviously good, but it was a bit of a surprise and makes setting up applications more complicated. They are working on improving the error message.
How to fix
1. Go to http://developers.facebook.com/apps/ and select the app you wish to fix.
2. At the bottom of the left hand menu click + Add Product link.
3. Select Web.
4. Enter your Site URL and hit save.
5. Hit Continue then keep clicking Next, ignoring all the code, until you get to Step 5
6. In the left hand menu you should now see Facebook Login, click the Settings menu item underneath it.
6. Under Client oAuth settings, where it says Use Strict Mode for Redirect URIs make sure it’s set to No and that your site URL is in the Valid OAuth redirect URIs box. Then the hit save.
7. You should now be able to connect your app as normal.