Here is the error.log of nginx server running on ubuntu 12.04.

2014/03/17 12:47:17 [error] 7939#0: *1 open() "/opt/nginx/html/mkl/authentify/signin" failed (2: No such file or directory), client: xxx.xxx.228.66, server: xxx.xxx.109.181, request: "GET /mkl/authentify/signin HTTP/1.1", host: "xxx.xxx.109.181"

In /opt/nginx/conf/nginx.conf, it is configured as following:

server_name xxx.xxx.109.181;
root /ebs/www/;
passenger_enabled on;
rails_env production;
passenger_base_uri /mkl;

The root of nginx server is pointing to /ebs/www/. However the nginx is accessing the /opt/nginx and throws out no such file error. What causes the problem? Thanks.