It’s very normal your Rails app has to run under a Rails version different from the one on Bluehost (or any other hosts). If so, we have to find a way to install our own Rails gem and let the application knows about it.
Install a new gem on Bluehost (or any other hosts) is easy, just run
gem install gem_name -v=gem_version
Next, we’ll let our app where our own gems are located. In your ~/.bashrc, added these: