Error running Development: Rails 3.x launcher script was found instead of Rails 4.x one.

When Upgrade from rails 3.2.x to rails 4.0.0, we found error like : Error running Development: Rails 3.x launcher script was found instead of Rails 4.x one. This is because new project structure of rails 4.0.0. To solve this you must copy 'bin' from you'r rails to you'r root project.