rails在部署的时候出现Cannot spawn application

rails在部署的时候出现
Cannot spawn application '/d/htdocs/app': The spawn server has exited unexpectedly.

环境：
centos
rails 3.0.6
passenger 3.0.7
ruby 1.8.7
nginx 0.8.35

查一下nginx的日志也许会有线索。