"bin/rails: No such file or directory" w/ Ruby 2 & Rails 4 on Heroku

I had this problem also since I upgraded to rails 4.0.0

Run this command

rake rails:update:bin

You can go here for more info https://devcenter.heroku.com/articles/rails4

After struggling with this for a bit, I noticed that my Rails 4 project had a /bin directory, unlike some older Rails 3 projects I had cloned. /bin contains 3 files, bundle, rails, and rake, but these weren't making it to Heroku because I had bin in my global .gitignore file.

This is a pretty common ignore rule if you work with Git and other languages (Java, etc.), so to fix this:

1. Remove bin from ~/.gitignore
2. Run bundle install
3. Commit your changes with git add . and git commit -m "Add bin back"
4. Push your changes to Heroku with git push heroku master

Steps :

1. bundle config --delete bin # Turn off Bundler's stub generator

2. rake rails:update:bin # Use the new Rails 4 executables

3. git add bin or git add bin -f # Add bin/ to source control

4. git commit -a -m "you commit message"

5. git push heroku master

6. heroku open