I starting having the same problem today:
Something which should never happen, happened. Sorry about that. If you try again, maybe it will work.
Error code: -32300
This only problem that I’m having is that I’m getting the error message when I try to reconnect to WordPress.com, therefore I cannot use Jetpack at all currently.
Your website needs to be publicly accessible to use Jetpack: site_inaccessible
Error Details: The Jetpack server was unable to communicate with your site [HTTP 403]. Ask your web host if they allow connections from WordPress.com. If you need further assistance, contact Jetpack Support: https://jetpack.me/support/
