Error: The site <URL> cannot be added since it is invalid or blocks Patchstack from accessing the site.

This error often appears when there is no public access to your website. Usually, it means that your server is protected using .htaccess and .htpasswd. To install the Patchstack plugin and connect our app to your website, it has to be publicly accessible for Patchstack as well, so you will have to remove the server authentication.