Did you get the answer to this question? I am facing similar issue on nginx.

2012/08/21 06:29:02 [debug] 27567#0: *13 http fastcgi record byte: 00
2012/08/21 06:29:02 [debug] 27567#0: *13 http fastcgi record byte: 01
2012/08/21 06:29:02 [debug] 27567#0: *13 http fastcgi record byte: 00
2012/08/21 06:29:02 [debug] 27567#0: *13 http fastcgi record byte: 00
2012/08/21 06:29:02 [debug] 27567#0: *13 http fastcgi record byte: 00
2012/08/21 06:29:02 [debug] 27567#0: *13 http fastcgi record byte: 00
2012/08/21 06:29:02 [debug] 27567#0: *13 http fastcgi record length: 0
2012/08/21 06:29:02 [error] 27567#0: *13 upstream closed prematurely FastC GI stdout while reading response header from upstream, client: 10.11.18.32 , server: , request: "GET /cgi-mod/nph-export_log.cgi?et=1357555736&primar y_tab=LOG&password=852c5469f9ba3c8bdf5bc8964ea3aded&auth_type=Local&user=a dmin&locale=en_US&secondary_tab=vpn_log&log=vpn_log HTTP/1.1", upstream: " fastcgi://unix:/var/run/fcgi_socket:", host: "10.11.22.51", referrer: "htt ps://10.11.22.51/cgi-mod/index.cgi?auth_type=Local&et=1357555726&locale=en _US&password=066f426d95d849b1d9d6f15849009e80&user=admin&primary_tab=LOG&s econdary_tab=vpn_log"
2012/08/21 06:29:02 [debug] 27567#0: *13 http next upstream, 8
2012/08/21 06:29:02 [debug] 27567#0: *13 free rr peer 1 4
2012/08/21 06:29:02 [debug] 27567#0: *13 finalize http upstream request: 5 02