How to restrict editing of Assignee field on a closed ticket?

[Autumn Justice]

Hi!

My goal is to restrict the ability to edit fields on closed tickets to only a group of Administrators.

I already managed to restrict almost every field on a ticket (epic link, story points, reporter, etc) using the property key jira.permission.edit.group.1=administrators, but for some reason, assignee is still able to be edited by non-admin users after the ticket has been closed.

How can I go about preventing this field from being edited post-close (except by admins)? 

[Nic Brough -Adaptavist-]

Welcome to the Atlassian Community!

You're almost there already with Jira.permission.edit.group - assigning an issue is a separate permission, so add another similar property - Jira.permission.assign.group 

[Autumn Justice]

Thank you! I did add that permission property in, but it seems that users without admin permission can still edit the assignee field post-close.

[Nic Brough -Adaptavist-]

Hmm.  Could you try  a complete block

Jira.permission.assign.denied

Documented at https://support.atlassian.com/jira-cloud-administration/docs/use-workflow-properties/