Heroku Addon Airbrake
Please review the Airbrake Docs. http://devcenter.heroku.com/articles/airbrake
If you have problems after upgrading, please check that you don't still have Hoptoad installed. You can do this by running
heroku config --long --app <app-name> | grep -E
"(AIRBRAKE_API_KEY|HOPTOAD_API_KEY)" heroku config:remove
HOPTOAD_API_KEY --app <app-name>