Version: saas~16.1+e

What are the steps to reproduce your issue?
customer logs in to account, retrieves SO and tries to download the digital file by clicking the link.

What is the current behavior that you observe?
customer gets a 500 internal server error page with the description  "The server encountered an internal error and was unable to complete your request. Either the server is overloaded or there is an error in the application." (the URL it's directed to is "/my/download?attachment_id=XXX"). 

What would be your expected behavior in this case? for the file to download correctly when clicked.