Heroku web app deployment error
This most likely has nothing to do with favicon.ico. H10 App Crashed means your server could not start, and every request sent to it is erring out. 
I recommend to use heroku restart, and look in the logs what is causing server to die on startup.
I'm getting an Application error when running my python heroku app and the logs show:
at=error code=H10 desc="App crashed" method=GET path="/favicon.ico" host=python-blackjack.herokuapp.com request_id=38f050c2-bc7e-499a-8112-ee7d4b66bf0c fwd="90.205.68.255" dyno= connect= service= status=503 bytes= protocol=https
does anyone know the issue/s 
thanks