My configuration now is: gzip on; gzip_min_length 1000; gzip_comp_level 6; gzip_proxied expired no-cache no-store private auth; gzip_types text/plain application/xml application/x-javascript text/css; #gzip_disable msie6; and the problem remains. Posted at Nginx Forum: http://forum.nginx.org/read.php?2,216030,216219#msg-216219