Heroku-18 stack has reached end-of-life

Change effective on 01 May 2023

Heroku-18, our stack based on Ubuntu 18.04 Long Term Support, was previously deprecated on June 22, 2022, and in accordance with our stack update policy has now reached end-of-life.

Apps using the Heroku-18 stack will continue to run, but will no longer receive security updates, and no new builds (code deployments) can be performed until apps are first upgraded to a more recent stack.

See the Heroku-18 End-of-Life FAQ for more information.