Heroku-16 stack builds are disabled

Change effective on 01 June 2021

Heroku-16, our stack based on Ubuntu 16.04 LTS, reached end-of-life on May 1st, 2021.

Effective today, June 1st, 2021, builds will no longer be allowed for Heroku-16 apps.

Existing apps using the Heroku-16 stack will continue to run, but should be upgraded to a more recent stack to receive security updates and restore the ability to deploy new code.

See the Heroku-16 End-of-Life FAQ for more information.