1. Save an attachment which has spaces in the name, e.g. typical word document
2. Try to click on this attachment within the issue.

Expected:
The attachment is downloaded/opened/displayed

Actual:
A page displays the 'Internal Server Error'

Notes:
I noticed that the internal server error page displayed the path to the attachment with %20 where there were spaces. Manually removing these and pressing enter does download the attachment. This is a temporary workaround but not long term given the volume of usage we are getting. Observed this with both Chrome & Firefox