spdy/2 support has been removed from the Firefox code base ( https://bugzilla.mozilla.org/show_bug.cgi?id=912550 ) and >= Firefox 27 will only support >= spdy/3. Firefox 27 will be released in January 2014 ( https://wiki.mozilla.org/RapidRelease/Calendar ) so there is some urgency in getting spdy/3(.1) support into nginx.by eddy1234 - Nginx Mailing List - English