Error Code -10520 when I try to connect to facebook

Could you try the following:

1) Go the Jetpack menu in your dashboard
2) Click on “My Jetpack” at the top of the page.
3) Click on “Disconnect Site from WordPress.com” if your site is currently connected to WordPress.com.
4) Confirm the disconnection.
5) Click on the Connect button to connect your site to WordPress.com again.

If that doesn’t help, can you please use Jetpack’s Debugger module to send us some more information about your site?

1) Go to the Jetpack page in your dashboard.
2) Click on the Debug link appearing at the bottom of the page.
3) Click the link that says “click here to contact Jetpack support.”
4) Fill in the description box and your name and email address.
5) Click the “Contact Support” button.

Thanks!

There’s no opportunity to end you the message privatly. But I got a red box which says:

Offenbar kann deine Website nicht richtig mit Jetpack kommunizieren.
SELF:
	Array
(
    [headers] => Array
        (
            [server] => nginx
            [date] => Mon, 25 Jul 2016 15:01:03 GMT
            [content-type] => text/plain;charset=utf-8
            [connection] => close
            [expires] => Wed, 11 Jan 1984 05:00:00 GMT
            [cache-control] => no-cache, must-revalidate, max-age=60
            [pragma] => no-cache
            [x-hacker] => Jetpack Test
            [x-ac] => 3.fra _dfw
            [strict-transport-security] => max-age=15552000
        )

    [body] => {"error":"Unknown Error","error_description":"An unknown error has occurred."}
    [response] => Array
        (
            [code] => 400
            [message] => Bad Request
        )

    [cookies] => Array
        (
        )

    [filename] =>
)

Could you copy all the data appearing under the “View Advanced Debug Results” link at the bottom of the page, and paste it in this contact form to send it to us?
https://jetpack.com/contact-support/

Thanks!

I did.