If you use the AddThis sharing plugin, you may incur in a problem: the iOS Facebook app will sometimes redirect shared links to http://example.com/%23.VVMxmH6d8SY.facebook instead of http://example.com/#.VVMxmH6d8SY.facebook as it should. This known issue break the link, and directs the user to a 404, or "Page Not Found", wasting that precious social traffic. If your site is running on an … [Read more...] about Fix the AddThis 404s on the Facebook iOS App – rewrite %23 to #