User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:15.0) Gecko/20120608 Firefox/15.0a2 Build ID: 20120608042008 Steps to reproduce: Opened the about:newtab page and clicked on a site, e.g. de.twitch.tv, went back to newtab page. Actual results: The site didn't have a thumbnail. Expected results: The site should have a thumbnail.
only happens on specific sites.
The missing thumbnails is due to the site using "no-cache, no-store" Thumbs are not shown when site uses that coding and Firefox does not show thumb as it could be a privacy issue. See https://bugzilla.mozilla.org/show_bug.cgi?id=760773 and its duplicate. marking as duplicate https://bugzilla.mozilla.org/show_bug.cgi?id=756881