Upstream: call ngx_http_run_posted_requests() on resolve errors. If proxy_pass to a host with dynamic resolution was used to handle a subrequest, and host resolution failed, the main request wasn't run till something else happened on the connection. E.g. request to "/zzz" with the following configuration hanged: addition_types *; resolver 8.8.8.8; location /test { set $ihost xxx; proxy_pass http://$ihost; } location /zzz { add_after_body /test; return 200 "test"; } Report and original version of the patch by Lanshun Zhou, http://mailman.nginx.org/pipermail/nginx-devel/2013-March/003476.html.