Hello, I am having the same problem as Gabriel and Brian.
Google led me to try the command "heroku run rails console" to give me another error report than the heroku H10 error from "heroku logs" (Gabriel and Brian, maybe this would be useful to you?), and I got the following:
Running rails console on secure-hamlet-3699... up, run.8080
to_specs': Could not find 'spring' (= 1.4.3) among 59 total gem(s) (Gem::LoadError)to_spec'
However, rvm gemdir gave me ~/.rvm/gems/ruby-2.2.0, and spring was definitely there in the gems directory.
I have tried a lot of other solutions online, but cannot seem to make any progress. heroku run:db migrate worked fine, I just get this page when using heroku open:
There were some git related complications I had to deal with earlier, and I'm using Fedora, not Ubuntu, but I seem to have fixed all of those.
My heroku logs are pretty long because of the number of different things I've tried to do to fix the problem, but I can paste the wall of text here if that would help. The only errors in the logs all look like this:
2015-11-18T21:08:52.013379+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/favicon.ico" host=secure-hamlet-3699.herokuapp.com request_id=c4cb04e6-e57c-4b69-84cd-05d0bba01a30 fwd="18.104.22.168" dyno= connect= service= status=503 bytes=
That is the last log entry currently.
I have also tried heroku restart, which did not fix the problem.
edit: (also no problems with pushing to heroku via "git push heroku master")