Web Server broken after Rails Deployment on AWS EC2 using Capistrano

I upgrade a Rails app on AWS EC2 using Capistrano with no erros. Previous version was worked fine.

But my Web Site complains as following.

"500 Internal Server Error If you are the administrator of this website, then please read this web application's log file and/or the web server's log file to find out what went wrong."

My deploy.rb file include following code.

after "deploy:restart", "deploy:cleanup" after "deploy:migrate", "deploy:migrate"

What should I do? Please help me. Urgent!