Issues with heroku deployment

I'm having trouble deploying to Heroku. An error occurs when starting the server.

base64.rb:59:in `decode64': undefined method `unpack1' for nil:NilClass

which happens in from /app/app/models/user/connected_account.rb:36:in `<class:ConnectedAccount>'

This looks like I'm not able to pull out access_token_encryption_key from my production credentials. But I've added the production.yml.enc to the project, which has the access_token_encryption_key set, and I've set the RAILS_MASTER_KEY to the contents of my production.key. 

I've tried to redo this quite a few times now, and no luck. Am I doing it wrong?

Ok, I added sendgrid config, and uploaded the changed production.yml.enc, and somehow it's just working now :)