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.
If your app is a Scala app, it must have a build.sbt in the root directory, and that file must be checked into Git. You can confirm this by running:
build.sbt
$ git ls-files build.sbt
If that file exists and is checked into Git, try running this command:
$ heroku buildpacks:set heroku/scala