A stack trace error occurs after a participant clicks a matrix cell to view contents. I believe the problem was caused by a file attachment I added to a guidance instructions area that was from a hidden folder. Further testing showed that when I removed the attachment from Items to attach, the problem went away.
The stack trace error is attached.
Steps to reproduce:
Coordinator/Instructor creates matrix
In one of the cells, guidance is added.
One of the guidance attachments is from a hidden folder
Matrix saved and published
Participant logs in clicks matrix cell with hidden folder's file and the stack trace error is exhibited