Excon not recognising my SSL route

Question

When pushing to Heroku, my db:migrate failed at the following:

!    Heroku client internal error.
Error:       Unable to verify certificate, please set `Excon.defaults[:ssl_ca_path] = path_to_certs`, `Excon.defaults[:ssl_ca_file] = path_to_file`, or `Excon.defaults[:ssl_verify_peer] = false` (less secure). (Excon::Errors::SocketError)

So, I added the following to the bottom of my production.rb file (my certs at in the root file)

Excon.defaults[:ssl_ca_path] = Rails.root

Same error.

So I then tried the fallback:

Excon.defaults[:ssl_verify_peer] = false

Same error.

I'm stumped, and have been going round in circles for hours. Any ideas?

Thanks in advance