URL blocked: This redirect failed because the redirect URI is not white-listed in the app's client OAuth settings

"URL blocked: This redirect failed because the redirect URI is not white-listed in the app's client OAuth settings"

If you're trying to connect your WordPress site to Facebook and you come across this error it's most likely because your website domain isn't correctly whitelisted in your Facebook App. Double check the steps in the Creating a Facebook App tutorial and ensure your domain is added in all the input fields listed.