Authentication failed! Facebook returned an invalid user id on Yith social login wordpress

Solution:

I had the same problem. I solve it by changing these lines:

\wp-content\plugins\yith-woocommerce-social-login\includes\hybridauth\Hybrid\Providers\Facebook.php: 27

public $scope = ['email'];

and

\wp-content\plugins\yith-woocommerce-social-login\includes\hybridauth\Hybrid\Providers\Facebook.php: 85

$accessToken = $helper->getAccessToken("https://[your-domain]/wp-content/plugins/yith-woocommerce-social-login/includes/hybridauth/?hauth_done=Facebook");

And

https://[your-domain]/wp-content/plugins/yith-woocommerce-social-login/includes/hybridauth/?hauth_done=Facebook must be registered in Valid OAuth Redirect URIs in FB administration