Heroku not updating css for rails app

Remember that you have to commit the changes locally before you can push them.

If you do a git status, it should be clean.

If it's not (my prediction):

git commit -am "Your commit message"
git push heroku master

Each time you make changes on your CSS you need to run the following commands on the terminal:

$bundle exec rake assets:precompile
$git add . 
$git commit -m "msg" 
$git push heroku master

If you have recently deleted a css file, you should also use 'git rm' to ensure that it has been removed from your repository. Otherwise heroku may still use it.

In my case it was because a previous developer had set up to do compiles locally instead of at deploy time. I had a manifest file that I needed to delete:

public/assets/manifest-<md5 hash>.json

Once I deleted that and pushed, heroku built my assets.