I was pushing the current git repository into the heroku. That online application was developed using Scala and IntelliJ. And I don\'t know how to fix this error.
There has to be a .git directory in the root of your project.
.git
If you don't see that directory run git init and then re-associate your remote.
git init
Like so:
heroku git:remote -a herokuAppName git push heroku master