Heroku: Your account has reached its concurrent build limit

We can cancel the current build. Or any ongoing build using below

heroku builds:cancel

You can check the list of builds using

heroku builds

Or you can cancel any build using build hash from the above result list.

In case builds command not working, you need to install it using

heroku plugins:install heroku-builds

Finally, I managed to resolve an issue with the help of the following 3 commands and it works:-

$ heroku plugins:install heroku-builds
$ heroku builds:cancel
$ heroku restart

For my case, heroku restart worked.

I had to try two of these answers back-to-back. Individually, they didn't work for me.

I needed to install heroku-builds with

heroku plugins:install heroku-builds

Then cancel the ongoing build with

heroku builds:cancel

And finally did a heroku restart.