I am unable to move an open issue through my workflow. I keep getting an error of "cannot assign issue to nonexistent user (username redacted). It seems that you have tried to perform an illegal workflow operation. If you think this message is wrong, please contact your Jira administrator."
I am using Jira Core v7.5.1 (I know it's end of life) We have had multiple contract companies do work on our instance of Jira, however none of them have left any continuity. Any help would be appreciated.
Is it a particular step/transition in your workflow that you are getting stopped it? If so, look at the post functions for that transition and see it is trying to assign the issue there.
One thing to watch is "Default Assignee" You can assign an issue to a "default assignee" The default assignee is defined in 1 of 2 place
Make sure that the default assignee is still with the company, and is a valid assignee. If not, please change it.
With components. make sure the Lead for each one is a real user, or else make sure the "Default Assignee" for the component is "Project Default"
Have you checked your permissions? Move issues is a specific permission within the project.
Settings | Project | Permissions | Move Issues
Make sure that you are in one of those permission sets (probably the Group) that has permission to move the issues through this project.
if you're not, first go to your project
Projects | users and roles | Add user to a role
and add yourself to the appropriate group that has this permission.