Facebook API error 191

I'm trying to integrate my project with Facebook. I'm taking baby steps at first and just trying to login, get a Facebook session, and get some user data. I'm developing it locally so my Facebook application settings are:

site URL: http://127.0.0.1:8888/mySite/

The canvas URL is the same as above. I haven't specified a site domain.

However, when I click on the login button, I get an error:

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.

At the moment I haven't written any server-side code to deal with redirects, etc. All I've done is add the JavaScript SDK based on the tutorial in Facebook for Websites.

What have I done wrong? It's obviously something to do with my Facebook application settings, but I can't see what!

Solution 1:

UPDATE:
To answer the API Error Code: 191
The redirect_uri should be equal (or relative) to the Site URL.

Tip: Use base URLs instead of full URLs pointing to specific pages.

NOT RECOMMENDED: For example, if you use www.mydomain.com/fb/test.html as your Site URL and having www.mydomain.com/fb/secondPage.html as redirect_uri this will give you the 191 error.

RECOMMENDED: So instead have your Site URL set to a base URL like: www.mydomain.com/ OR www.mydomain.com/fb/.

I went through the Facebook Python sample application today, and I was shocked it was stating clearly that you can use http://localhost:8080/ as Site URL if you are developing locally:

Configure the Site URL, and point it to your Web Server. If you're developing locally, you can use http://localhost:8080/

While I was sure you can't do that, based on my own experience (very old test though) it seems that you actually CAN test your Facebook application locally!

So I picked up an old application of mine and edited its name, Site URL and Canvas URL: Site URL: http://localhost:80/fblocal/

I downloaded the latest Facebook PHP-SDK and threw it in my xampp/htdocs/fblocal/ folder.

But I got the same error as yours! I noticed that XAMPP is doing an automatic redirection to http://localhost/fblocal/ so I changed the setting to simply http://localhost/fblocal/ and the error was gone BUT I had to remove the application (from privacy settings) and re-install my application and here are the results:

After that, asked for the publish_stream permission, and I was able to publish to my profile (using the PHP-SDK):

$user = $facebook->getUser();
if ($user) {
    try {
        $post = $facebook->api('/me/feed', 'post', array('message'=>'Hello World, from localhost!'));
    } catch (FacebookApiException $e) {
        error_log($e);
        $user = null;
    }
}

Results:

Solution 2:

For me, it was a missing app domain. Go into the app, and make sure that you have the root of your site set up as an app domain. See screenshot.