This section provides info on a known issue in the X-Payment Cloud connector add-on.
You are unable to sign in to your X-Payments Cloud account. The X-Payments Cloud settings page in your store's Admin area shows the "Access from an unauthorized domain" message:
Clear cookies in your browser. If it does not help, confirm your account registration email using the link that was sent to your email after the creation of your account. If still no luck, try using a different web browser.