The legacy Cedar-10 stack has been deprecated and reached its end-of-life on November 4, 2015. Applications may continue running, however you will not be able to push to your application without upgrading to Cedar-14 first.
Due to changes in the glibc library on Cedar-14, apps may see different memory consumption behavior on that stack. See the Performance Differences section for details.
You can follow the process defined in this doc if you need to verify if your application might not run properly in newly upgraded cedar. This process defined in this doc guides you to create a new-staging app (its just another Heroku app). This app will have the new cedar. You will deploy your code to this app and test if it works fine.
However, if you are confident with your code correctly running on the Cedar-14 or you already have a staging app setup in Heroku, you can just do as following
First, set stack on the production app to Cedar-14:
$ heroku stack:set cedar-14 -a <app name> stack set, next release on production-app will use cedar-14 Run `git push heroku master` to create a new release on cedar-14
To create the new release, push to your production app:
$ git push heroku master
If the production app is not working after you changed the stack to Cedar-14, you can temporarily revert back to the Cedar-10 stack until you’ve debugged and resolved the issue.
First you need the release version of the previous Cedar-10 release:
$ heroku releases === production-app Releases v13 Deploy 973c3f7 email@example.com 2014/07/09 10:55:16 v12 Deploy ddb317d firstname.lastname@example.org 2014/07/07 10:46:26 ...
By rolling back, the stack will automatically be reverted to the stack the rollback release was created on.
$ heroku rollback v12
Your production app is now running on Cedar again.