Facebook Share in a private message is not working : "Attachment Not Found: The attachment could not be found." ASP.net

Question

I have implemented the Facebook share button as follows:

Layout.master

...
    <meta name="description" content="Vote for this referendum.">
    <meta property="og:title" content="<%= og_title %>">
    <meta property="og:url" content="http://www.articolo75.it/">
    <meta property="og:locale" content="en_US">
    <meta property="og:site_name" content="Articolo75.it">
    <meta property="og:type" content="website"> 
    <meta property="og:image" content="assets/img/favicon/ms-icon-310x310.png"> 
...

ReferendaDetail.aspx

...
    <li>
    <a href="http://www.facebook.com/share.php?u=http://185.117.152.92:8081/ReferendaDetail.aspx" class="facebook">
    <i class="fa fa-facebook-f" aria-hidden="true"></i>
    </a>
    </li>
...

"Share to News Feed or Story" is working well.

But when I tried to "Share in a Private Message", I get an error saying "Attachment Not Found: The attachment could not be found."

Please try to check this issue on my web page. There is a Facebook share button under the big title "Contro Parlamento".

Any suggestions or ideas would be greatly appreciated. Thanks!

Answer 1

等待大神答复