Problem with Facebook cache: Page not Found on future posts in Wordpress

facebook_purge.php

<?php

// Issues with sharing posts on Facebook: http://www.passwordincorrect.com/issue-with-sharing-wordpress-posts-to-facebook/

// Add this chunck of code in your functions.php or anywhere else in your theme files.

// Register action for post status transitions
add_action( 'transition_post_status' , 'purge_future_post', 10, 3);

// Check if the new transition is publish, for correctness you could check if $old_status == 'pending', but I want that every post (which is published) is cached again (just to be sure). 
function purge_future_post( $new_status, $old_status, $post ) {
    if($new_status == 'publish') {
        purge_facebook_cache($post);
    }
}

// Ping Facebook to recache the URL.

function purge_facebook_cache($post_id) {
    $url = get_permalink($post_id);
    $fb_graph_url = "https://graph.facebook.com/?id=". urlencode($url) ."&scrape=true";
    $result = wp_remote_post($fb_graph_url);
}

?>

I just ran into this issue myself. Thanks for the code :-)

please tell me how to use this.

Can the same thing be used for Google+? This seems to work wonders, but g+ is acting wonky, so if an example with g+ could help, that'd be great!

You need to add it to your theme's functions file (functions.php)
You do not need the opening and closing php tags as the functions file will already have it.
PS: Thanks @leandersikma for the code. Hopefully this resolves the issues I am had with Facebook incorrectly caching a post as a 404.

This works great but you might sometimes get the FB API rate-limiting you. If that happens you can create a Facebook app and use that to authenticate:

wp_remote_post(
    'https://graph.facebook.com/',
    [
        'body' => [
            'id' => get_permalink($post_id),
            'scrape' => 'true',
            'access_token'  => FACEBOOK_APP_ID . '|' . FACEBOOK_APP_SECRET,
        ]
    ]
);

I just used your script within my Theme Functions.php (funtions.php) and my complete blog turned blank. It doesn't really matter what I do it won't come back up unless I skip a few pages back. I deleted the script and updated it but it's still blank. What now?

EDIT-

I managed to get rid of the script and website is working again. But still 404 page not found....