Troubleshooting Sign-In using Facebook

From WHMCS Documentation

Invalid details not saved. Please verify your details and try again.

You may receive the above error message when attempting to configure your Facebook API Credentials. It indicates that the values provided are not able to successfully authenticate with the Facebook API.

If you receive this message, double check your API Key and Secret and try again.

Can't Load URL: The domain of this URL isn't included in the app's domains.

If you see a popup containing an error message as pictured below when attempting to Sign in using Facebook, this indicates that the URL configured within your Facebook App is no longer valid.

Please refer to Configuring Sign-In using Facebook for instructions regarding how to set the URL for your Facebook API App.