Heroku build timeout 2021

If you have a Heroku app that has worked for many years and is suddenly experiencing a Duplicate build version error or if you are following an old tutorial from before 2021 and see the following cryptic error message in the build log.

 !
 !   Build timed out while waiting to start.
 !

Heroku has recently updated their default git branch name from master to main. As a result of Black Lives Matter, words like master and slave are no longer kosher even when used to describe objects. Simply run the following command to push code from your local repository to the new main branch.

git push heroku master:main