Heroku: Cannot run more than 1 Free size dynos

Question

I was trying to run

heroku run rake db:migrate

And was getting the error

Cannot run more than 1 Free size dynos.

Answer 1

Most Efective

in console run:

heroku ps

the result is some like this:

run.4859 (Free): up 2016/01/12 21:28:41 (~ 7m ago): rails c

So the numbers 4859 represent the session that is open and needs to be closed. To fix the error you need to run(Obviusly, replace the number 4859 by the number obtained):

heroku ps:stop run.4859

It is a very simple solution.