Cannot create comment on issue in Jira Software Edited

[Jon Hagstad]

We run Jira Service Desk (4.1.0), Core and Software (8.1.0) on premise on a Ubuntu 16.04 server.
Https (ssl) is configured according to the official guides (iptables redirect to 8443) and it is been working fine.
We use MS-SQL2014 as database server.
We access Jira with the base URL.

However today a user discovered that he could not comment on a Jira Software issues and got the error message below:

I have checked all of the Jira logs without any error message, including:

atlassian-jira.log
catalina.out


I have tried to comment on several issues without any success, my user has the correct Jira permissions.

Could you please assist?

Regards

Jon

[Matt Doar__ LinkedIn]

Does the comment have an emoji in it? That can cause this error

[Jon Hagstad]

No emojis in the comment.

It seems that only the user the issue has been assigned to can in fact comment on the issue.
Is this by design?

The error message seems to be the wrong one though if its due to missing permissions