at=error code=H10 desc="App crashed" method=GET path="/favicon.ico" request_id=fwd= dyno= connect= service= status=503 bytes= protocol=https code example

Example: at=error code=H10 desc="App crashed" method=GET path="/

Logged in as admin, 
inside the App in question, 
the “More” button in the upper right has a “Restart all dynos” option.