"Error loading documents" when clicking a link from an FYI Summary Notification

Issue
I have received an email notification that was created from a Summary Notification Automation Process. Clicking the link in the message gives the following error:
"Error loading documents".

Cause
There were two Summary Notifications that were generated by the same Automation Process to the same Role, for example, Partner. The Email notification that was sent has mixed up the URL and has timed out.

Solution
Usually, you would only require one notification per person. Delete the additional step in the Automation so that only one notification is sent per person.