The message isn't in English so I've no idea what error you're seeing. Please switch the site to English and retry then provide the full error message as this will allow me to find where the message is coming from exactly. Your registration form having no inputs is strange though. Are you using CB Conditional to condition fields? Is CB Core in CB > Plugin Management public and published?

It looks like it's doing that because there's no fields available to the user. Make sure you've fields available to registration within CB > Field Management and that the tab they're on is published. By default CB works out of the box so you've changed something in regards to the core registration fields or their tab. Core fields (username, name, password, email, etc..) are placed on the Contact Info tab by default.