Today I was working with an application I\'ve had running on Heroku for a few months now and in an attempt to get something working I ran in my development environment:
If you running Rails 4.0 or above, rake assets:clean has been replaced with rake assets:clobber.
However, there are some current problems with clean and clobber with regards to permanently deleting assets. You can follow the issue here. https://github.com/heroku/heroku-buildpack-ruby/issues/123