
Seems a similar report was opened https://jira.atlassian.com/browse/CONF-43601
this was fixed in 1000.279.0 14/Sep/2016 - but has current comments - last user comment was Jun 2019. Maybe related ?
To reproduce when updating or when creating a Jira issue
add attachment (eg .jpeg)
add text to comment
Save
response is "We could'nt save your comment"
have to cancel
Work around is save attachment without comment
add comment after save.