failed to push some refs to [email protected]

This error means that the upstream repository has made commits that would be lost if you were to push. First do a "git pull" to merge, and then push again.

In Heroku,you may have problems with pushing to master branch. I just had to start a new branch using

git checkout -b masterbranch

and then push using

git push heroku masterbranch

please try as above!

Execute this:

$ rake assets:precompile
$ git add .
$ git commit -m "Add precompiled assets for Heroku"
$ git push heroku master

Source: http://ruby.railstutorial.org/ruby-on-rails-tutorial-book