I executed following command
openssl req -new -x509 -days 999 -nodes -out myapp.key -keyout myapp.pem
And then I tried following command
heroku ssl:add myapp.pem myapp.key --app myapp
I am getting following error message
! Pem is invalid / Key is invalid
I am using MacBook Pro.
I already paid $20 to heroku and am using "Hostname Based Custom SSL".